1. Intro to Statistics (Every Quiz in Unit 1)
A brand of popcorn instructs users to microwave for 90-120 seconds on high. A student wonders what the ideal microwave time for popcorn might be and designs an experiment to find out. Bags of popcorn are placed in the microwave for different lengths of time: 90 seconds, 100 seconds, 110 seconds, and 120 seconds. Also, 2 types of microwaves with different power capacity will be used: 900 watts and 1,000 watts. At the end of the experiment, the number of unpopped kernels will be counted. Using 3 lengths of time and 2 types of microwaves describes which part of the experiment? the levels the treatments the response variable the experimental units
A.
A clothing company is considering a new insulation for winter coats. To collect customer satisfaction data on the new insulation, the company is considering two methods. Method 1: The company offers the first 50 employees who volunteer to try out a coat with new insulation if they will report their satisfaction level after one month. At the end of the month, the 50 volunteers describe their satisfaction with the coat's performance. Method 2: The company takes 50 volunteers and randomly assigns 25 of them to coats with the new insulation and the other 25 to coats with the current insulation. All volunteers wear the coats for a month and then describe their satisfaction with the coats' performance. Which method describes an experiment? Method 2 is an experiment because both groups report their satisfaction with the coats. Method 1 is an experiment because all volunteers receive coats with the new insulation. Method 2 is an experiment because volunteers are assigned one of the two insulation types. Method 1 is an experiment because the volunteers' satisfaction with the new insulation can be measured.
C.
To find the ideal temperature for baking muffins, a student plans an experiment to assess the taste and texture of muffins baked at different temperatures. The student pours 3 batches of muffins from the same batter into baking cups and assigns them to different oven temperatures: 350 degrees, 375 degrees, or 400 degrees. Each batch is baked for 10 minutes, and after appropriate cooling time, the muffins are assessed for taste and texture. What is the explanatory variable in this experiment? the baking time the 3 batches of muffins the baking temperature the taste and texture of the muffins
C.
To increase attendance for a flower show, the organizers have chosen flower shops in the area to offer discount coupons to their customers. Half of the stores receive discount coupons for admission, while the other half of the stores receive two-for-one admission coupons. The organizers then compare the number of each type of coupon redeemed at the show. What are the explanatory and response variables in this scenario? The explanatory variable is the number of coupons redeemed. The response variable is the type of coupon. The explanatory variable is each chosen flower shop. The response variable is the number of coupons redeemed. The explanatory variable is the type of coupon. The response variable is number of number of coupons redeemed. The explanatory variable is the attendance at the flower show. The response variable is the number of attendees who used coupons.
C.
A farmer would like to determine if a new liquid fertilizer is an improvement compared with the fertilizer currently used. To collect data, two methods are considered. Method 1: Visit a local farm currently using the new liquid fertilizer and measure the heights of plants grown at the farm. Method 2: Choose a plot of land and divide it into 16 smaller plots. Randomly select 8 of the plots to use the new fertilizer and 8 of the plots to use the current fertilizer. Measure and compare plant heights in the 16 plots. Which statement about these methods is true? Method 1 is an experiment because the farm uses the new fertilizer. Method 2 is an experiment because there are 16 different plots used. Methods 1 and 2 are both experiments because both use the new fertilizer. Method 2 is an experiment because the plots are randomly assigned a fertilizer.
D.
A home-improvement store offers a new brand of lawn food that claims to reduce the number of weeds by 30% over a different brand of lawn food. To test the claim, a homeowner plans to use the new brand of lawn food on half of his lawn and the original brand on the other half. The homeowner will count the number of weeds that appear after a month on each half of the lawn. A neighbor explains that there may be confounding variables, such as shade, that might also explain the relationship. Which statement best describes the effect of the confounding variables? Because of confounding variables, the homeowner should only put the new lawn food on shady spots and the original brand on sunny spots. Because shade is a primary cause of weed growth, the brand of lawn food used in shady or sunny spots will not affect the number of weeds. If the half of the lawn with the new lawn food shows fewer weeds after a month, this will prove the new lawn food is better at stopping weed growth. The parts of the lawn that receive the new lawn food may also get more shade than other parts of the lawn, and the shade might also cause fewer weeds.
D.
An auto-parts store offers a fuel additive that claims to increase a vehicle's gas mileage. The additive is poured into a vehicle's gasoline tank after the tank is filled. To measure the claim, 30 taxi drivers receive a bottle of the additive to use the next time they fill their gas tank. The drivers then compare their gas mileage with the additive to their gas mileage before the additive was used. What is the response variable in this scenario? the age of the car the 30 cars used in the study the use of the additive the gas mileage after the additive is used
D.
An auto-parts store offers a fuel additive that claims to increase a vehicle's gas mileage. The additive is poured into a vehicle's gasoline tank after the tank is filled. To measure the claim, the store offers a free bottle of the additive to customers who drive SUV's, who then provide information about their gas mileage on the store website. A customer argues that the type of vehicle could be a confounding variable in this study. Which statement best describes the effect of the confounding variable? Because vehicles of different sizes may respond similarly to the additive, it should be easy to conclude whether the additive improves gas mileage. Because vehicles of different colors may show differences in gas mileage, the additive may improve the gas mileage in some vehicles but not in others. Because owners of different types of vehicles may choose not to use the additive, those vehicles will not show an improvement in gas mileage. Because vehicles of different sizes may respond differently to the additive, it may be difficult to conclude whether the additive improves gas mileage for all vehicles.
D.
Two methods are proposed to measure the effectiveness of a brand of sunscreen. Method A: Survey adults visiting a beach on a busy weekend. Ask each adult which brand of sunscreen they are using, and assess their arms for sun exposure. Method B: Volunteers are randomly assigned to one of two brands of sunscreen. Each volunteer is asked to report back at the end of the day, and their arms are assessed for sun exposure. Which statement is a correct interpretation of these methods? Both methods are experiments because sun exposure is assessed in both methods. Both methods are observational studies because neither method attempts to influence responses. Method A is an experiment because it compares many brands of sunscreen, while method B is an observational study. Method B is an experiment because it randomly assigns volunteers a sunscreen, while method A is an observational study.
D.
To increase attendance for a flower show, flower shops in the area offered discount coupons to their customers. Show attendance was higher this year, which the organizers attributed to the many discount coupons attendees used. However, the organizers are warned that weather could be a confounding variable in interpreting the rise in attendance. Which statement could explain the effect of confounding? Because the weather was worse last year, fewer coupons were distributed compared to this year. Because the weather was similar in both years, it most likely played no role in the attendance increase. Because coupons were handed out this year and not last year, the weather was different this year compared to last year. Because the weather was generally better this year compared to last year, the attendance may have increased.
Not C.
How far do US workers travel to get to their jobs? To estimate the average distance workers travel, a website includes a survey where adults can share their daily commute distance. What are the population and sample in this setting? The population is all US workers. The sample is adults who respond to the survey. The population is all visitors to the website. The sample is adults who respond to the survey. The population is all US workers. The sample is the mean distance of adults who respond to the survey. The population is all adults who respond to the survey. The sample is the average commute distance of adults who respond.
Not b. Probably a.
To attract business, a clothing store mails discount coupons to residents of a town. To estimate the proportion of the store's shoppers who are using the coupons, the store manager selects a random sample of 100 customers who visit the store on a weekend. The manager finds that 38 of them are using the coupons mailed to their homes. Which of the following describes the sample in this setting? all residents of the town the 38 shoppers who used coupons the 100 randomly selected shoppers all shoppers in the store on the weekend
Not b. probably c.
The president of the student council wants to survey the student population about parking. She decides to use a random number table to take a random sample of 100 of the 1,020 students at the school. What is the smallest number of digits that should be used to label the population? 1 2 3 4
Not c. Correct: d. 4
An economist would like to estimate the proportion of young adults who have college debt. An online survey invites young adults to share information about their level of college debt. Which of the following describes the survey design and potential bias? This is voluntary response and is likely to overestimate the proportion of young adults with college debt. This is voluntary response and is likely representative of the proportion of young adults with college debt. This is voluntary response and is likely to underestimate the proportion of young adults with college debt. This is a convenience sample and is likely to overestimate the proportion of young adults with college debt
This is voluntary response and is likely to overestimate the proportion of young adults with college debt.
A band director is trying to decide what music to play for the halftime show. To get a sample, the director divides the band into groups based on their grade (freshmen, sophomores, juniors, and seniors). Then she randomly chooses a group and surveys every member of the chosen group. Which sampling method was used? cluster sampling simple random sampling stratified random sampling systematic random sampling
a.
A biology student wanted to determine if using fertilizer would promote plant growth. One hundred plants were randomly assigned to one of two groups: one that used the fertilizer, and one that did not use a fertilizer. Which of the following is a benefit of having replication in the experiment? Having a large number of plants receiving the treatments will allow for a good comparison of the differences in plant growth between the two groups. Having a large number of plants receiving the treatments will not allow for a good comparison of the differences in plant growth between the two groups. Replication is not needed in this experiment. One plant receiving each type of treatment is enough to determine if the difference in plant growth is due to the fertilizer. Repeating the experiment will allow the student to compare the differences between the plants that received the fertilizer the first time and the plants that received the fertilizer the second time.
a.
A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers placed an ad online asking for volunteers to participate in the study, and 100 subjects replied. They are informed that one group will receive a new cream and the other group will receive a cream with no active ingredient. The researchers believe that sun exposure may affect the cream's effectiveness. The subjects are then asked about their outdoor activities, and 42 of the subjects state they spend more than 50% of their day outside. All subjects are exposed to poison ivy and given their cream. They are asked to return in three days and report their level of irritation. Which of the following describes a randomized block design? The subjects are grouped based on their outdoor activity. The 42 subjects are randomly assigned to the two treatment groups. The remaining 58 subjects are also randomly assigned to the two treatment groups. The subjects are numbered 1-100, and these numbers are entered into a random number generator. Fifty numbers, ignoring repeats, are generated and these subjects receive the new cream. The remaining 50 receive the inactive cream. The subjects are paired based on similar age. Two marbles, one red and one blue, are placed in a bag and mixed. If the first subject picks a red marble, then that subject will receive the new cream and the other subject will receive the inactive cream. If it is blue, then the opposite will occur. This is done for all 50 pairs. The subjects are grouped based on their outdoor activity. The researchers flip a coin and if it lands on heads, then the group with the most sun exposure will receive the new cream and the other group will receive the inactive cream. If the coin lands on tails, then the group with the most sun exposure will receive the inactive cream and the other group will receive the new cream.
a.
A tire company wants to determine if tires made with a new type of tread will last longer than the tires made with the original type of tread. The company has access to 24 different vehicles. The vehicles will be driven for one year and the depth of the remaining tread will be measured. The average depth for the new type of tread will be compared to the average depth of the original type of tread. Which of the following describes a randomized block design for this experiment? There are six vehicles of each vehicle type: sedan, SUV, minivan, and truck. For each type, three vehicles will be randomly selected to receive tires with the new tread and the other three vehicles will receive tires with the original tread. Each vehicle is numbered 1-24, and these numbers are put into a random number generator. The first 12 unique numbers represent the vehicles that will receive the tires with the new tread. The remaining 12 vehicles will receive the tires with the original tread. The vehicles will be put in groups of two based on the size of the vehicle, with the largest two put together, the next largest two, etc. For each of the 12 pairs, the largest vehicle will get tires with the original type of tread and the other vehicle in the pair will get the new type of tread. There are six vehicles of each vehicle type: sedan, SUV, minivan, and truck. Each vehicle type is numbered 1-4, and these numbers are entered into a random number generator. The first two unique numbers selected will represent the group of vehicles that will receive tires with the new type of tread. The remaining 2 groups will receive tires with the original tread.
a.
A tire company wants to determine if tires made with a new type of tread will last longer than tires made with the original type of tread. The company decides to put tires with the new tread on 10 different vehicles and tires with the original tread on 10 different vehicles. "New" is written on one slip of paper and "Original" is written on another slip of paper. The two slips are placed in a bag and thoroughly mixed. A vehicle is selected and a slip is drawn. The corresponding tread of tires is assigned to the vehicle. The slip is put back into the bag and mixed. The next vehicle is selected and a slip is drawn. The corresponding tread is assigned to the vehicle. This procedure continues until all 20 vehicles have been assigned tires of the new or original types of tread. Does this procedure describe a completely randomized design for this experiment? Yes, the tires are randomly assigned to each vehicle. Yes, there are two treatments, new and original treads. No, even though randomness is used, the procedure does not ensure that an equal number of vehicles are in both groups. No, the company did not use 20 of the same type of vehicle to receive both treatments, the new and original treads.
a.
Aeronautical researchers have developed three different processes to pack a parachute. They want to compare the different processes in terms of time to deploy and reliability. There are 5,100 objects that they can drop with a parachute from a plane. Using a table of random digits, the researchers will randomly place the items, labeled 0001-5100, into three equally sized treatment groups suitable for comparison. Carry out the random assignment using the given selection from a table of random digits, starting with the first row and first column. Which list assigns the first five items to the process 1 group? 2719, 2825, 3031, 2628, 3562 6011, 8572, 2719, 5769, 2825 2719, 2825, 3031, 2628, 2719 601, 18, 57, 227, 1957
a.
A farmer sows 100 seeds of a new type of corn and wants to quickly determine the yield, or total number of ears of corn, for the crop when it has matured. He decides to take a simple random sample of the crop. Which of the following correctly labels the population? 00-99 01-99 0-99 1-100
a. 00-99
How far do US workers travel to get to their jobs? A researcher would like to collect information on the commute distance traveled by workers and considers many methods for collecting data. Which of the following methods represents a voluntary response sample? Workers are invited to share their daily commute distance on a website. Workers at a large company are each asked to share their daily commute distance. The researcher stands in a public area and asks each adult to share their daily commute distance. The researcher takes a random sample of adults from a large town and asks each to share their daily commute distance.
a. Workers are invited to share their daily commute distance on a website.
Several members of a running club would like to survey the rest of the members to determine which 5K race the club should enter. They decide to sample 10 of the 78 members and have them fill out a survey about their race preference. Which of the following would be a simple random sample? Write each member's name on an equal-sized slip of paper. Place the slips of paper in a bag and shake. Draw 10 slips of paper and survey the members selected. Write each member's name on an equal-sized slip of paper. Place the slips of paper in a bag. Draw 10 slips of paper off the top and survey the members selected. Write each member's name on a scrap of paper. Fold the pieces of paper and place them in a bag. Draw 10 slips of paper off the top and survey the members selected. Write each member's name on a scrap of paper. Fold the pieces of paper, place them in a bag, and shake the bag. Draw 10 slips of paper and survey the members selected.
a. Write each member's name on an equal-sized slip of paper. Place the slips of paper in a bag and shake. Draw 10 slips of paper and survey the members selected.
Many people enjoy taking cruises for their vacations. Each cruise ship has different options and features. Which of the following is an example of a continuous quantitative variable that might be reported about each cruise ship?
average speed in the ocean
A band director is trying to decide what music to play for the halftime show. She surveys the marching band students to get their opinions about which music they would prefer. Which of the following sampling techniques would provide a stratified random sample that would accurately represent the students' opinions? Have a computer randomly sort the band members, then select the first 30. Randomly select 2 students from each type of instrument (trumpet, saxophone, clarinet, etc.). Randomly pick a letter of the alphabet and survey every student whose last name begins with that letter. Randomly pick a year of students (freshman, sophomore, junior, or senior) and survey every student from the selected group.
b.
A biology student wanted to determine if using fertilizer would promote plant growth. One hundred plants were randomly assigned to one of two groups: one that received fertilizer, and one that did not receive fertilizer. Which of the following statements is true about the benefits of random assignment? The variability between each plant may not be evenly distributed between the two groups, so any observed differences in the plant growth between the two groups would not be due to the fertilizer. The variability between each plant would be evenly distributed between the two groups, so any observed differences in the plant growth between the two groups are more likely due to the fertilizer. The variability between each plant may not be evenly distributed between the two groups, so any observed differences in the plant growth between the two groups may or may not be due to the fertilizer. The variability between each plant would be evenly distributed between the two groups, so any observed differences in the plant growth between the two groups are guaranteed to be due to the fertilizer.
b.
A business is interested in employees' job satisfaction. The regional manager places a name card for every employee into a bowl and randomly selects 10 cards. Which sampling method was used? cluster sampling simple random sampling stratified random sampling systematic random sampling
b.
A city government is considering raising the local income tax to pay for improvements to government facilities. A private citizen opposes the plan and stands on a busy street to survey residents with the question, "Do you agree that wasteful spending is a serious problem in our local government?" The results of the survey will most likely suffer from which type of bias? This is nonresponse bias because many who are asked the question may choose not to respond. This is question wording bias because the question leads those surveyed toward a desired response. This is voluntary response bias because those with a passionate opinion may choose to participate. This is undercoverage bias because many in the population will not have the opportunity to register an opinion.
b.
A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers placed an ad online asking for volunteers to participate in the study. One hundred subjects replied, and they were informed that one group would receive the new cream and the other group would receive a cream with no active ingredient. All 100 subjects were exposed to poison ivy. Fifty were then assigned to the group with the new cream, and 50 were assigned to the group with the cream with no active ingredient. Which of the following is a benefit of having replication in the experiment? Repeating the experiment will allow the researchers to compare the differences between the subjects that received the new cream both times. Having a large number of subjects receiving the treatments will allow for a good comparison of the differences in level of irritation between the two groups. Having a large number of subjects receiving the treatments will not allow for a good comparison of the differences in level of irritation between the two groups. Replication is not needed in this experiment. One subject for each type of treatment is enough to determine if the reduction in level of irritation is due to the new cream.
b.
A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers put an ad online asking for volunteers to participate in the study. One hundred subjects replied, and they were informed that one group would receive the new cream and the other group would receive a cream with no active ingredient. All 100 subjects were exposed to poison ivy. Fifty were then assigned to the group with the new cream, and 50 were assigned to the group with the cream with no active ingredient. After three days, the subjects' level of irritation was measured. The technicians who surveyed the subjects' level of irritation as well as the subjects did not know which group received which treatment. What type of experiment is this? single blind double blind placebo effect controlled experiment
b.
A paper company wants to survey its employees about a new policy on sales commissions. Which of the following would result in a stratified random sample? Give a survey to everyone who was eating lunch in the break room that day. Randomly select 2 people from each department (sales, customer service, accounting, etc.) Put everyone's name on a slip of paper and randomly pull out 10 names. Using an alphabetized list of employees, randomly select a starting point and survey every 4th person after that.
b.
A random sample of adults in a large US city responded to a series of questions about their use of public transportation. The results of the survey showed that 520 of the 838 adults in the sample (62%) have used public transportation in the past week. How might the results of the survey be biased in obtaining an estimate of all US residents who use public transportation? Because not all residents in this US city were asked to participate, the survey may underestimate usage of public transportation. Because the sample includes only residents in one US city, the survey may overestimate the proportion of US adults who use public transportation. Because those surveyed may choose not to answer, the survey may underestimate the proportion of US residents who use public transportation. Because the survey includes a random sample of residents in one US city, the survey should provide an accurate estimate of the proportion of US adults who use public transportation.
b.
A researcher is comparing three new formulas for grass killer. To conduct the experiment, the researcher purchases 30 pieces of sod from various vendors to use in the study. The 30 pieces of sod are laid out in three different areas. The researcher places three slips of paper in a bowl labeled formula 1, formula 2, and formula 3 and randomly picks a piece of paper to apply that formula to the sod in the first area. Then the researcher picks again and applies that formula to the second area. Finally, the last formula is used on the last area. Which component is missing from the researcher's process? The researcher should not have laid out the pieces of sod in different areas. The researcher did not randomly assign the pieces of sod to the treatment groups. The researcher did not randomly pick the vendors when purchasing the pieces of sod. The researcher did not use randomization when selecting the pieces of sod from the vendors.
b.
A veterinarian knows that the supplement glucosamine is beneficial for dogs' joints. He wants to determine if a supplement with both glucosamine and chondroitin would be more beneficial than glucosamine alone for dogs' joint health. The veterinarian asks the owners of dogs with known joint issues if they would be willing to have their dog participate in his study, and 32 owners agree to the study. The veterinarian also knows that breed and age may affect the results of the experiment. Which of the following designs would be most appropriate for this experiment? Completely randomized design: Randomly assign the treatments to the dogs. Matched pairs design: Block the dogs based on breed. Then, within each block, pair the dogs based on age. Randomly assign the treatments to each dog in the pairs. Randomized block design: Block the dogs based on breed. Then, randomly assign half of the dogs in each block to receive glucosamine only and the other half to receive glucosamine with chondroitin. Observational study: The veterinarian should randomly select patient records. Then, use the joint health of dogs that use glucosamine only and those that use glucosamine with chondroitin.
b.
An education researcher is interested in comparing the learning outcomes of students who are taught a lesson using five different teaching techniques. Using a table of random digits, the researcher needs to randomly place 75 students, labeled 01-75, into five equally sized treatment groups suitable for comparison. Carry out the random assignment using the given section from a table of random digits, starting with the first row and first column. Which list assigns the first seven students to the technique 1 group? 8, 7, 2, 6, 5, 4, 1 26, 54, 72, 19, 70, 62, 30 26, 54, 72, 26, 19, 70, 62 87, 26, 54, 00, 88, 77, 72
b.
Many adults owe money from their college loans for years into their professional careers. A newspaper would like to estimate the proportion of all adults in the city who have debts from college loans. To collect data, a random sample of 300 young adults between the ages of 25 and 35 is asked, "Do you have more than $5,000 in current college debts?" 68% of those sampled reported that they do have more than $5,000 in college-related debts. How might this sample be biased in obtaining an estimate of all adults in the city who have college debts? Because young adults were randomly selected, this sample should provide an unbiased estimate of the proportion of adults with college debts. Because only young adults were sampled, undercoverage bias may cause the newspaper to overestimate the proportion of all adults who have college debts. Because some young adults may not honestly report their debts, response bias may cause the newspaper to underestimate the proportion of adults with college debts. Because adults with college debts may be less likely to respond, voluntary response bias may cause the newspaper to underestimate the proportion of adults who have college debts.
b.
Many large cities have considered or passed proposals that ban the use of plastic grocery bags in stores. A concerned student would like to measure if residents of her hometown would consider a similar ban on plastic bags. Standing in a busy shopping area, the student approaches adults and asks, "Items made of plastics are a dangerous, growing source of pollution to our world's oceans and threaten many animal species. Given this, would you support a ban on plastic shopping bags in our city stores?" How might the results of this survey be biased in estimating the proportion of all town residents who would support a ban on plastic bags? The student may overestimate support for a plastic bag ban because only adults in the shopping area were chosen to participate. The student may overestimate support for a plastic bag ban because the wording of the question may influence adults to support a ban. The student may underestimate support for a plastic bag ban because the wording of the question may influence adults to not support a ban. The student may underestimate support for a plastic bag ban because some adults may not want to answer questions about the environment.
b.
Many large cities use taxes on entertainment tickets to pay for improvements to public facilities, like stadiums, arenas, and concert venues. A city council proposal would increase the current ticket tax in order to raise funds for a new public concert hall. Council representatives plan to conduct a survey outside of a large concert in the summer and ask selected adults if they would support an increase in the ticket tax to pay for the new concert hall. Which type of bias will most likely affect the survey results? This is response bias because it is likely that many who respond will not provide a truthful opinion of the ticket tax. This is undercoverage bias because only those attending the concert will have an opportunity to register an opinion. This is nonresponse bias because many who are asked about the ticket tax may choose to not provide a response. This is voluntary response bias because many vocal supporters of the ticket tax may demand to register their opinion.
b.
A greenhouse owner wants to test the effectiveness of a new fertilizer on African violets. She has 60 violet seedlings that were grown for 8 weeks. She wants to test the new fertilizer on 10 of the plants, and decides to use a random number table to select a simple random sample. Which of the following correctly labels the population of violets? 00-60 01-60 0-60 1-60
b. 01-60
A school cafeteria wants to survey a random sample of 50 students about the quality of food. During one lunch period, every 5th student who walks through the cafeteria door is surveyed until 50 students are selected. Which of the following statements is true about this sample? This is a random sample, and it is a simple random sample. This is neither a random sample nor a simple random sample. This is not a random sample, but it is a simple random sample. This is a random sample, but it is not a simple random sample.
b. This is neither a random sample nor a simple random sample.
A teacher assigns 10 questions for homework and wants to randomly pick 3 questions to be graded. He writes the numbers 1-10 on equally sized slips of paper and places them in a bag. He shakes the bag and selects 3 slips of paper. Is the sample of 3 questions a simple random sample? Yes, because the paper slips were equally sized. Yes, because the paper slips were equally sized and the bag was shaken. No, because there are only 10 questions. No, because the questions were selected using a bag.
b. Yes, because the paper slips were equally sized and the bag was shaken.
A biology student wants to determine if using a fertilizer would help promote the growth of new babies in spider plants. The student has access to 90 baby spider plants of three varieties: green, variegated, and curly. There are 30 plants of each variety. They all are potted in the same amount and type of soil, given the same amount of water, and exposed to the same amount of light. The numbers 1-30 are written on slips of paper, placed in a hat, and mixed thoroughly. A plant is selected and a slip of paper is drawn. If the slip has the numbers 1-15, then the plant will receive fertilizer. If the slip has the numbers 16-30, the plant will not receive fertilizer. A green spider plant is selected and a slip of paper is drawn. This plant is placed in the treatment group indicated by the number, and the slip is not put back in the bag. The slips are mixed again, the next green spider plant is selected, and a slip is drawn. The plant is placed in the treatment group indicated by the number. This procedure is repeated until all 30 green spider plants are assigned to treatments. The numbered slips are placed back in the bag and this procedure is repeated for the remaining types of spider plants. After one year, the shoots will be counted for each plant. Which of the following best describes the design for this experiment? observational study matched pairs design randomized block design completely randomized design
c.
A local vet wants to survey his clients about their satisfaction regarding the care their pet received. He groups all of the clients by the type of pet they have (dog, cat, bird, exotic, or multiple), then randomly selects 5 people from each group. Which sampling method was used? cluster sampling simple random sampling stratified random sampling systematic random sampling
c.
A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers put an ad online asking for volunteers to participate in the study. One hundred subjects replied, and they were informed that one group would receive the new cream and the other group would receive a cream with no active ingredient. All 100 subjects were exposed to poison ivy. Fifty were then assigned to the group with the new cream, and 50 were assigned to the group with the cream with no active ingredient. After three days, the subjects' level of irritation was measured. Of the 50 subjects that were assigned to the cream with no active ingredient, 15 stated they had less irritation. What is this called? placebo control group placebo effect placebo control
c.
A researcher is interested in whether using mental imagery can help people remember specific details when given information. To conduct the experiment, the researcher selects the treatment group by placing numbered slips of paper in a hat and randomly selecting half of the numbers, making sure to mix the slips between each selection. Which component is missing from the researcher's process? The researcher did not use randomization to select the treatment and control groups. The researcher did not randomly choose the participants for the experiment. The researcher did not label the participants with numbers before placing the numbers in a hat. The researcher did not use enough random selections to make the correct number of groups.
c.
A restaurant chain would like to measure the proportion of customers who are generally satisfied with the service provided by its staff. At the end of the meal, as the check is delivered to the table, the server asks those at the table to rate their satisfaction with the service provided as "Very Satisfied," "Satisfied," or "Not Satisfied." During a one-week period, 147 customers were surveyed and 135 (93%) reported they were either Satisfied or Very Satisfied. What type of bias may be present in the survey results? This is nonresponse bias because customers may not respond to the question. This is question wording bias because the question may be misleading to some customers. This is response bias because customers may not respond truthfully to the server. This is voluntary response bias because customers can choose to be part of the sample.
c.
A student wants to determine if different types of soil, A and B, affect the propagation of African violets. One hundred leaves from the same variety of African violet were selected. The leaves were then randomly assigned to 50 pots with type A soil and the remaining leaves were put into the 50 pots with type B soil. All of the pots were given the same amount of water and arranged in 10 rows of 10 pots near a window for light. The 50 pots with type A soil were placed closest to the window. At the end of two months, the pots with type A soil had the greatest number of pots with new growth, so the student concluded that soil type A was more effective that soil type B. Is this a valid conclusion? Yes, because the leaves were randomly assigned, this evenly distributed the variability in the leaves; therefore, type A soil is more effective than type B soil. Yes, because the amount of water and light were controlled, this may have reduced the variability in the response; therefore, type A soil is more effective than type B soil. No, because the pots with type A soil were closest to the window, they received more light, which may have led to the new growth. No, because only African violets were used, replication was not properly implemented; therefore, we cannot conclude that type A soil was more effective.
c.
A study is testing the effectiveness of a new allergy medication. Sixty volunteers who reported they experience allergies were randomly assigned to one of two groups: one with the new medication, and another with a placebo. After two weeks, the subjects' level of allergic symptoms was surveyed. Which of the following is a true statement concerning the use of a placebo? The placebo is given to one group of subjects to see if the subjects receiving the placebo experience fewer allergic symptoms than the subjects taking the new medication. The placebo is given to one group of subjects to see if the subjects receiving the placebo experience more allergic symptoms than the subjects taking the new medication. The placebo is given to one group of subjects to see if the subjects receiving the placebo think they have fewer allergic symptoms because they believe they are taking the new medication. The placebo is given to one group of subjects to see if the subjects receiving the new medication think they have fewer allergic symptoms because they believe they are taking the new medication.
c.
A teacher wants to know if burning a scented candle affects students' performance on pop quizzes. In the experiment, there will be a treatment group and a control group each taking their quizzes in a room that either does or does not have a scented candle burning. Why is randomization important when setting up an experiment to answer this research question? to ensure that both groups have a nice mix of students to ensure that the two groups have the same number of students to ensure that both groups are roughly equivalent regarding students' preparedness, anxiety levels, and study skills to ensure that the rooms for both groups are approximately the same regarding time of day, temperature, sound control, and lighting
c.
A teacher wants to know if burning a scented candle affects students' performance on pop quizzes. In the experiment, there will be a treatment group and a control group each taking their quizzes in a room that either does or does not have a scented candle burning. On a randomly chosen day, the first 15 students who arrive to class will be the control group while the last 15 students who arrive will be the treatment group. Which statement best describes the composition of the groups? The characteristics of the two groups should be roughly equivalent because both groups have 15 students. The characteristics of the two groups should be roughly equivalent because the students were split into groups on a randomly chosen day. The characteristics of the two groups might not be roughly equivalent because the students were not labeled and given a random number to place them in one of the groups. The characteristics of the two groups might not be roughly equivalent because students who arrive around the same time might be friends and have similar preferences for scented candles.
c.
A veterinarian knows that the supplement glucosamine is beneficial for dogs' joints. He wants to determine if a supplement with both glucosamine and chondroitin would be more beneficial than glucosamine alone for dogs' joint health. The veterinarian asks the owners of dogs with known joint issues if they would be willing to have their dog participate in his study, and 32 owners agree to the study. Sixteen dogs are randomly assigned to the glucosamine group and the remaining 16 are assigned to the glucosamine with chondroitin group. After 6 months, the dogs' joint health is measured for each treatment and compared. The results of the study were inconclusive and the veterinarian decides to do the experiment again. He gets 24 volunteers and decides that he needs to use a randomized block design. Which variable would not be an appropriate variable for blocking? age size color of coat breed
c.
An education researcher is interested in comparing the learning outcomes of students who are taught a lesson using five different teaching techniques. There are 75 students in the school who can participate in the experiment. Using a table of random digits, the researcher will randomly place the students into five equally sized treatment groups suitable for comparison. How many unique random numbers must be read from the table of random digits? 5 15 60 75
c.
Some newer phones provide a screen time summary, which shows the amount of screen time for a user in a given week. A student would like to estimate the mean screen time for all phone users. She asks a random sample of 50 students at her school to share their screen time for the past 24 hours. The mean screen time for the chosen students is 2.73 hours. Which statement is an appropriate interpretation of the results? All students probably have screen times close to 2.73 hours. To obtain a better estimate of mean screen time, more students should be surveyed. Because of undercoverage, 2.73 likely underestimates the mean screen time of all phone users. 2.73 hours is a suitable estimate for mean screen time of all phone users because a random sample was taken.
c.
A community group would like to raise funds to pay for improvements to the community swimming pool. The group's leaders are considering a number of methods to assess community interest in raising funds. Which of the following uses convenience sampling? The group sends a survey through the mail to all community residents. The group places a survey on a webpage where residents can register their support. The group stands outside a shopping center and asks residents who enter if they support raising funds. The group selects a random sample of homes in the community, and residents in those homes are interviewed.
c. The group stands outside a shopping center and asks residents who enter if they support raising funds.
A large city offers many venues for watching a concert. A listing of concert venues for the city includes the following information: the number of seats, the age of the venue, the number of nearby parking spaces, and the location of the venue (inside or outside). What are the individuals in the data set? concert venues seats ages of the venue parking spaces
concert venues
A biology student wanted to determine if using fertilizer would promote plant growth. One hundred plants were randomly assigned to one of two groups as shown in the design web. Which of the following accurately describes the benefit of comparison in the experiment shown in the design web? There is no need for comparison in this experiment. The overall growth of the plants can be compared to see which plants benefit the most from fertilizer. The growth of the plants in the treatment group only can be compared to see if the fertilizer had a significant effect. The growth of plants in the treatment group and the control group can be compared to see if the fertilizer had a significant effect.
d.
A florist wants to determine if a new additive helps extend the life of cut flowers longer than the original additive does. The florist selects 20 flowers of different types and puts each flower in its own vase with the same amount of water. She positions the vases so they also receive the same exposure to light. She numbers the flowers 1-20, and places these numbers on equal-sized slips of paper. The slips are placed in a hat and mixed thoroughly. A slip is chosen and the corresponding flower receives the new additive. After the hat is shaken, another slip is chosen and the corresponding flower also receives the new additive. This procedure continues until 10 flowers have been assigned to receive the new additive. The remaining 10 flowers receive the original additive. Is this a randomized block design for this experiment? Yes, each flower is randomly assigned to the treatments. Yes, the flowers were placed in their own vases, and received the same amount of water and light. No, only 20 flowers were used in the experiment. No, the flowers were not put into groups first and then randomly assigned the two additives.
d.
A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers placed an ad online asking volunteers to participate in the study, and 100 subjects replied. They are informed that one group of 50 will receive a new cream and the remaining group of 50 will receive a cream with no active ingredient. As each subject enters the study facility, the researchers flip a coin. Heads means the subject goes to room A and tails means the subject goes to room B. The subjects in room A will receive the new cream and the subjects in room B will receive the inactive cream. All subjects are exposed to poison ivy and given their cream. They are asked to return in three days and report their level of irritation. Does this procedure describe a completely randomized design for this experiment? Yes, the subjects will all be exposed to poison ivy and then apply the cream. Yes, the subjects are receiving either the new cream or the inactive cream. No, the subjects are asked to return in three days. It is possible that some may not return, which will introduce bias into the results. Yes, the subjects are assigned to the two treatment groups completely by chance.
d.
A research group is comparing the learning outcomes of students who are taught a lesson using four different teaching techniques. There are 75 students in the school who can participate in the experiment. Using a table of random digits, the researchers will randomly place the students into five equally sized treatment groups suitable for comparison, four of which will receive a different teaching technique and one of which will remain a control group. Which design is the most appropriate for this experiment? Randomly number each person with 1, 2, 3, 4, or 5. Assign the students to the treatment groups based on their label. Select a student, and identify the first digit reading from left to right on a random number table. If the first digit is 1 or 2, assign that student to the technique 1 group. Similarly, digits 3 or 4, 5 or 6, 7or 8, and 9 or 0 go with the technique 2, technique 3, technique 4, and control groups, respectively. Repeat this process for each student. Number each student from 1 to 75. Reading the numbers from left to right on a random number table, identify 60 unique numbers from 1 to 75. Assign the students whose labels are the first 15 numbers to the technique 1 group. Assign the students whose labels are the second 15 numbers to the technique 2 group. Repeat this process two more times to assign the technique 3 and technique 4 groups. Finally, assign the remaining students to the control group. Number each student from 00 to 74. Reading the numbers from left to right on a table of random numbers and looking at two digits at a time, identify 60 unique two-digit numbers from 00 to 74. Assign the students whose labels are the first 15 numbers to the technique 1 group. Assign the students whose labels are the second 15 numbers to the technique 2 group. Repeat this process two more times to assign the technique 3 and technique 4 groups. Finally, assign the remaining students to the control group.
d.
A researcher is comparing three new formulas for grass killer. To conduct the experiment, the researcher purchases 30 pieces of sod from a local vendor and selects the treatment groups by placing slips of paper numbered 1-30 in a hat. To make three groups for the three formulas, the researcher randomly selects 10 numbers, making sure to mix the slips between each selection, to get the formula 1 group. Then the researcher selects 10 more numbers to get the formula 2 group. The remaining 10 numbers make up the formula 3 group. Which component is missing from the researcher's process? The researcher did not randomly pick the vendor. The researcher did not randomly pick the 30 pieces of sod. The researcher did not assign a treatment to each group of sod. The researcher did not label the pieces of sod before randomly selecting them.
d.
A shoe company wants to test an updated model of a running shoe to test its wear after one month of running. They recruit 50 people who run on a regular basis to participate in their study. They will have the runners wear the shoes when they run for one month. After one month, the wear on the shoes will be determined using the depth of the tread and flexibility of the toe box. The wear of the new and original models will then be compared. Which of the following describes a randomized block design for this experiment? The subjects are numbered 1-50 and these numbers are put into a random number generator. The first 25 random numbers, ignoring repeats, represent the subjects assigned to the new model group. The remaining 25 subjects will wear the original model of shoes. The subjects' names are written on equal-sized slips of paper and placed into a hat. A researcher then reaches in and pulls out 25 slips of paper. These subjects are assigned to the new model group. The remaining 25 subjects will be assigned to the original model group. The 50 subjects are paired based on running ability. The fastest two runners are paired together, the next fastest two, etc. For each pair of runners the researcher will flip a coin. If the coin lands on heads, then the first runner will receive the new model of shoes and the second will receive the original model. If the coin lands on tails, the first runner will receive the original model of shoes and the second runner will receive the new model of shoes. The 50 subjects are grouped based on running ability. Twenty runners classify themselves as competitive runners and the remaining 30 classify themselves as recreational runners. For the competitive group, the runners' names are written on equal-sized slips of paper and placed into a hat. The slips are shuffled, and the first 10 runners wear the new model of shoes and the other 10 wear the original model. The same procedure is used to assign the shoes to the recreational group.
d.
A tire company wants to determine if tires made with a new type of tread will last longer than the tires made with the original type of tread. The company has access to 24 different vehicles. The vehicles will be driven for one year and the depth of the remaining tread will be measured. The average depth for the new type of tread will be compared to the average depth of the original type of tread. Which of the following describes a matched pairs design for this experiment? Each of the 24 vehicles is numbered 1-24. These numbers are put into a random number generator. The first 12 unique numbers generated will represent the vehicles that will receive the tires with the new tread. The remaining 12 vehicles will receive the tires with the original tread. There are six vehicles of each vehicle type: sedan, SUV, minivan, and truck. For each type, the vehicles will be numbered 1-6, and a random number generator will be used to pick three unique numbers. These three vehicles will receive tires with the new tread and the other three vehicles in the group will receive tires with the original tread. There are six vehicles of each vehicle type: sedan, SUV, minivan, and truck. Each vehicle type is numbered 1-4, and these numbers are entered into a random number generator. The first two unique numbers selected will represent the group of vehicles that will receive tires with the new type of tread. The remaining two groups will receive tires with the original type of tread. The vehicles will be put into groups of two based on the size of the vehicle, with the largest two put together, the next largest two, etc. For each of the 12 groups of two, one of the vehicles is selected and a coin will be flipped. If it is heads, this car will receive tires with the new tread and the other vehicle will receive tires with the original tread. If it is tails, then the opposite will be done.
d.
An education researcher is interested in comparing the learning outcomes of students who are taught a lesson using five different teaching techniques. There are 75 students in the school who can participate in the experiment. Using a table of random digits, the researcher will randomly place the students into five equally sized treatment groups suitable for comparison. Which number range would be needed to label the students correctly? 0-4 1-5 00-75 01-75
d.
Executive leadership wants to survey employees at a grocery store that is open 24 hours a day. They are interested in getting surveys from people from every job title (cashier, stocker, manager, etc.) Which of the following uses systematic random sampling? Survey 3 randomly chosen cashiers, then repeat that process with the stockers, managers, etc. Randomly select 1 of the 3 shifts (morning, afternoon, or night), and survey all the employees who work that shift. List all of the employees by their employee ID number. Have the computer randomly select 25 of the numbers, and survey those employees. List all of the employees by their employee ID number. Survey the 11th person on the list (with the number 11 being randomly chosen), then survey every 10th person on the list after that.
d.
Some government leaders propose allowing oil companies to drill in currently protected lands that may be rich in oil reserves. Environmental researchers argue that drilling in such lands would be harmful to the surrounding ecosystem. To measure support for drilling in such lands, an oil company representative uses random-digit telephone dialing to contact adults in the region and measure opinion for increased drilling. One question in the survey asks, "Given that an increase in drilling could result in increased tax revenue and additional jobs to the region, would you support a proposal to allow drilling in lands currently protected from drilling?" What type of bias could be most likely affecting the survey results? This is undercoverage bias because some segments of the population will be excluded from the sample. This is response bias because those selected for the survey may not provide truthful opinions about oil drilling. This is voluntary response bias because those most passionate about drilling will be more likely to register an opinion. This is question wording bias because the information given at the start of the question may lead those surveyed towards a desired response.
d.
To estimate the proportion of city residents who shop online, a researcher visits a mall on a weekday morning and asks people she encounters to share their experiences with online shopping, including this question: "Do you shop online at least once each week?" The results show that 32% of shoppers shop online at least once per week. Which of these describes a likely source of bias present in the survey results? Response bias may be present because people may not be truthful with their responses. Question wording bias may be present because the question asked may exclude important information. Nonresponse bias may be present because people in a mall may not want to answer questions. Undercoverage bias may be present because people in the workforce and many younger people could be excluded.
d.
Which of the following is an advantage of using stratified random sampling? Stratified random sampling saves time and money. Stratified random sampling requires knowledge of the entire population. Stratified random sampling can be used even when there is not a list of the population. Stratified random sampling provides more precise estimates than simple random sampling.
d.
The owner of a greenhouse wants to test the effectiveness of a new fertilizer on African violets. She has 60 violet seedlings that were grown for 8 weeks. She wants to test the new fertilizer on 10 of the plants, and decides to use a random number table to select a simple random sample. She labels the violets 01-60. Refer to the given line from a random number table. Which numbers represent the first 5 plants selected? 60633 78034 99602 83440 55120 61551 33, 03, 49, 02, 40 06, 33, 03, 49, 02 60, 63, 37, 80, 34 60, 37, 34, 28, 40
d. 60, 37, 34, 28, 40
A hotel rewards club wants to randomly select 100 of its 5,000 members to participate in a survey. The club wants to determine if people's opinions differ based on age. There are 2,200 members between the ages of 25 and 50, and there are 2,800 who are age 51 or older. The club decides to randomly select 44 members between the ages of 25 and 50, and 56 members ages 51 and older. Is the sample of 100 members a simple random sample? Yes, because the hotel rewards members were randomly selected for the sample. Yes, because each hotel rewards member has the same chance of being selected. No, because the sample of 100 is too small a sample to represent the population. No, because each sample of 100 does not have the same chance of being selected.
d. No, because each sample of 100 does not have the same chance of being selected.
An automotive website would like to estimate the percentage of drivers who own their cars, rather than lease their cars. Which of these survey methods would not provide a convenience sample to estimate the percentage who own their cars? a survey of adults at an auto parts store a survey of all adults attending a car show a survey of people in a car dealership an online survey for sharing data about their cars
d. an online survey for sharing data about their cars
A golf course has 18 holes. A guidebook provided to golfers includes useful information about each hole, as shown below. What are the individuals in this data set?
holes
A movie theater offers many movie selections for its customers. The table below shows a summary of five movies currently offered and whether the movie is appropriate for children. What are the individuals in the data set? movie titles movie types lengths critics' scores
movie titles
A company that manufactures golf balls produces a new type of ball that is supposed to travel significantly farther than the company's previous golf ball. To determine this, 40 new-style golf balls and 40 original-style golf balls are randomly selected from the company's production line on a specific day. The balls are then placed in a bag and shaken. A golf pro then selects a ball and hits it. The distance the ball travels is then measured. The bag is shaken again, and the golf pro selects another ball to hit. She continues this procedure until all 80 of the golf balls are hit. Has the principle of comparison been addressed in this experimental design? Yes, because the balls are randomly selected, the distances of the new ball can be compared to the distances of the original ball. Yes, because the original ball type is included in this experiment, the distances the different balls travel can be accurately compared. No, because a placebo ball was not used, a comparison cannot be made to determine if the new ball travels significantly farther. No, because all of the new type of balls are not hit first, the distances they travel cannot be compared to the distances of the original ball.
not a.
Executives for a grocery store chain want to survey their employees about a new policy regarding break times. To get a representative sample of 40 employees, they randomly select 10 people from each of the different job titles at the store (cashier, bagger, stocker, and manager). Which sampling method was used? cluster sampling simple random sampling stratified random sampling systematic random sampling
not a.
Researchers would like to assess the overall health of white pine trees in a state park. The park has a paved road that runs through the middle of the park. To select trees to assess for damage, the ranger parks at the side of the road and chooses 100 trees near the road to assess for damage. Which of the following statements best describes the bias that may arise from the results? Because only 100 trees were selected, the overall damage of trees in the park may be underestimated. The ranger should take another sample of trees near the road and compare it to the first sample to reduce bias. Because a random sample of trees was chosen, the sample should provide a suitable estimate of the overall health of the trees. Trees near the road may have more damage than trees away from it, so the results may overestimate the overall damage of the trees.
not a. maybe: d.
Race organizers want to survey the participating runners on the difficulty of the running course. Which of the following most effectively uses cluster sampling? Separate the runners into men and women, then randomly select 20 men and 20 women. Organize the runners into groups (elite runners, fast runners, moderate runners, and walkers). Randomly select a group, and survey all the runners in that group. Put the same number of marbles as runners into a bag, with 20 of the marbles being red. Have each runner select a marble from a bag at the finish line. If they choose a red marble, they take the survey. Place the runners into groups based on the seconds part of their finishing time (0:00-0:05, 0:06-0:10, etc.). Randomly select 2 of these groups, and survey every runner within the chosen groups.
not b.
A statistics student considered many methods for collecting data from adults to estimate support for lowering the voting age to 16 years old. Which of the following methods would be least likely to include sampling bias? a random sample of 500 adults in the state a random sample of 200 students at a large high school a survey of people leaving the local mall on the weekend an online survey where adults are invited to share their opinions
not b. probably d.
The president of the student council wants to survey the student population about parking. She decides to take a random sample of 100 of the 1,020 students at the school. Which of the following correctly labels the population? 1-1020 01-1020 001-1020 0001-1020
not b. 01-1020 Correct: d. 0001-1020
A teacher assigns 10 questions for homework and wants to randomly pick 3 questions to be graded. The teacher assigns each homework question a digit from 0 to 9. Refer to the given line from a random number table. Which numbers represent the 3 homework questions selected? 60600 38034 99602 83440 55120 61551 6, 3, 8 6, 0, 6 6, 0, 3 6, 0, 0
not b. 6, 0, 6 Correct: c. 6,0,3
A teacher has 36 students who were randomly assigned to 6 rows of 6 desks. She wants to survey the students about the homework policy. Which of the following uses cluster sampling? Roll a fair number cube. Use the number rolled to pick a row of students. Survey every student in that row. List the students according to their grade in the class. Survey one A student, one B student, etc. For each row, flip a coin. If it is heads, survey all the boys in that row. If it is tails, survey all the girls in that row. Select a student by rolling a fair number cube twice. The first roll gives the row number, and the second roll gives the seat number. Then repeat.
not c.
A large retirement community provides many activities for its residents. The activity director is considering adding a trivia night on Tuesday evenings if there is enough interest from the residents. To measure interest in the trivia night, the activity director leaves a printed survey in residents' mailboxes, on which the resident can express whether they are interested. Of the 68 surveys returned, 55 expressed interest. Which of these describes the type of bias in this survey and a likely direction of the bias in estimating overall community support for the trivia night? This is nonresponse bias. The result overestimates support for trivia night. This is nonresponse bias. The result underestimates support for trivia night. This is undercoverage bias. The result overestimates support for trivia night. This is undercoverage bias. The result underestimates support for trivia night.
not c. probably a.
To attract business, a clothing store mails discount coupons to local residents. To estimate the proportion of the store's shoppers who are using the coupons, the store manager selects a random sample of 100 customers who visit the store on a weekend. The manager finds that 38 of them are using the coupons mailed to their homes. Which of the following describes the population in this setting? all residents of the town the 38 shoppers who used coupons the 100 randomly selected shoppers all shoppers in the store on the weekend
not c. probably a.
A teacher wanted to determine the effectiveness of two different learning tools—a computer program or a hands-on approach—for a particular concept she was preparing to teach. She will assign her students to one of the two methods to spend the whole class time to learn this concept. Which of the following variables would be moderated due to random assignment? the teacher time spent in class computer experience the different learning tools
not d.
Researchers would like to assess the overall health of white pine trees in a state park. Which of the following methods for choosing the trees to assess would be considered a convenience sample? A ranger hires employees to assess every tree in the park. The 100 trees closest to a ranger station are assessed for damage. A grid map of the park is used, and 100 random points on the grid are chosen and used to select the trees to assess. Each tree in the state park is tagged with a number, and 100 random numbers that represent the trees are selected and assessed for damage.
not d.
The CEO of a company wants to determine if taking the employees to a company retreat would boost their morale. He decides to use a random number table to survey a simple random sample of 50 of the 250 employees. How many digits should he use? 1 2 3 4
not d. 4 Correct: c. 3
Several members of a running club would like to survey the rest of the members to determine which 5K races the club should enter. They decide to sample 10 of the 78 members and have them fill out a survey about the races. Which of the following procedures would produce a simple random sample? Give each member a unique number from 01 to 78. Use a random number table and select the first 10 numbers between 01 and 78. Survey these members about their race preference. Give each member a unique number from 01 to 78. Use a random number table and select the first 10 two-digit numbers between 01 and 78. Survey these members about their race preference. Give each member a unique number from 01 to 78. Use a random number table and select 10 unique two-digit numbers between 01 and 78. Survey these members about their race preference. Give each member a random number from 01 to 78. Use a random number table and select 10 unique two-digit numbers between 01 and 78. Survey these members about their race preference.
not d. Give each member a random number from 01 to 78. Use a random number table and select 10 unique two-digit numbers between 01 and 78. Survey these members about their race preference. Correct: c. Give each member a unique number from 01 to 78. Use a random number table and select 10 unique two-digit numbers between 01 and 78. Survey these members about their race preference.
A family visits a car show to research information on vehicles they might consider purchasing. Brochures for each vehicle provide helpful information for the vehicle. Which of the following is an example of a discrete quantitative variable that might be included in the brochure? number of seats type of transmission presence of a sunroof fuel efficiency (in mpg)
number of seats
An airline uses many different types of airplanes. Information regarding some of the airplanes is given in the table below. Which of the variables is a continuous variable? number of seats seat width Wi-Fi first-class
seat width
Auto racing is a sport enjoyed by many people. In each race, there may be up to 25 cars on the racetrack. Which of the following is NOT an example of a quantitative variable you might use to describe a car in a race? the brand of car the number of tires used the number of laps completed the average speed (in mpg)
the brand of car
A manager of a grocery store collects data on each shopper who uses the self-checkout lanes on a Saturday morning. Which of the following is an example of a discrete quantitative variable that might be recorded in this setting? the gender of each shopper the shopper's use of coupons the number of items for each shopper the time each shopper spends completing the transaction
the number of items for each shopper
A visitor guide for a downtown area lists many restaurants. Which of the following is an example of a quantitative variable the guide could report for each restaurant? the zip code of the restaurant the number of seats in the restaurant the type of cuisine the restaurant offers a restaurant critic's letter grade (A-F)
the number of seats in the restaurant
A veterinarian is visited by many pets and their owners each day. Before the doctor attends to each pet, an assistant records information including the type, age, weight, and height of each pet. Which of the variables is a categorical variable? type age weight height
type
