Chapter 4 test
In order to estimate the amount of time students spend on homework, the principal at a high school plans to survey a sample of students. Because the principal believes that different grade levels have different amount of homework, the plan is to select separate random samples of freshmen, sophomores, juniors, and seniors. What type of sample did the principal perform? a. A simple random sample b. A stratified random sample c. An experiment d. A cluster sample
b
Mr. Rodriguez has a home room with 38 students and needs to select 4 students as representatives to serve on the principal's advisory board. In order to be fair, he decides to select a simple random sample. He obtains a list of the students' names in alphabetical order and numbers the students according to their position on the list. He writes the numbers on pieces of paper and puts the numbers in a bag. Which of the following is not a requirement for his procedure to be considered a simple random sample? a. Each student should receive a unique number from 1 to 38 b. He needs to place each paper back into the bang before selecting the next student c. Each slip of paper should be the same size d. He needs to mix the bag throughly before he selects each piece of paper
b
The department of tourism in the state of Colorado was interested in the proportion of skiers that prefer snowboarding to traditional skiing. A group of 50 skiers was selected at the largest ski resort in the state and asked if they preferred snowboarding to traditional skiing. Which of the following correctly describes the population and sample for this survey? a. The population is all resident in Colorado and the sample is all skiers in the state b. The. population is all skiers at the resort and the sample is the 50 skiers selected c. The population is the 50 skiers in the group and the sample is all skiers at the ski resort d. The population is all skiers in Colorado and the sample is all skiers at the resort
b
The newspaper at a school wants to find the average time students spend on homework each night. Which of the following samples will likely not be biased because it utilizes random sampling? a. Print out surveys that will be filled out by all of the AP students b. Assign each student at a school a different number and use a random number generator to pick 50 different numbers, the sample will be the corresponding 50 students c. Ask the first 100 students that arrive at school in the morning d. Have one teacher on campus ask all of their students
b
An experiment is conducted to see if advertisements affect the choice of snack a person eats. Twenty teenage volunteers are randomly assigned to watch a television program. One group of volunteers will watch the program with no ads and the other group will watch the same program, but with ads about healthily snack. After the program, the teenagers will be o freed healthy and unhealthy snacks. What is the purpose of random assignment in the context of this experiment? a. So that if there are many teenager that enjoy healthy snack, they will be all be placed into the same group b. So that if two of the volunteers are friends, they will be split into different groups c. So that each group will have exactly ten volunteers d. So that both groups of volunteers are roughly equivalent at the beginning of the experiment
d
Which statement below best describes the ethical requirements for studies involving human subjects? a. All individuals who are subjects in the study must give their informed consent b. All of the above are required for a study to be considered ethical c. All studies should be reviewed in advance by an institutional review board d. All of the data gathered about the individuals must be kept confidential
b
A company had developed a new product called Plantgrower Fertilizer. They claim the new product will help plants grow faster and taller than plants that do not receive the product. To test this, the company designs an experiment that has 20 planter boxes. In ten randomly selected planter boxes, Plantgrower Fertilizer is added to the soil and the other ten planter boxes do not receive the added fertilizer. Beside the added fertilizer to the soil, each planter planter box is treated the same, such as the amount of water used to grow the plants. At the end of the experiment, the average height of the plants for each type of planter box is computed to see if the new fertilizer does help plants grow faster and taller. Which of the following identifies the control group and why is this necessary to have a control group? a. The planter boxes with no added fertilizer, so we have a baseline for comparing the effects of the Plantgrower Fertilizer b. The planter boxes with Plantgrower fertilizer, so we can control the conditions for the experiment and make sure they are the same for each planter box, such as the amount of water used to grow the plants c. The planter boxes with no added fertilizer, so we can control the conditions for the experiment and make sure they are the same for each planter box, such as the amount of water used to grow the plants d. The planter boxes with Plantgrower fertilizer, so we can see how much more the plant grew with the new fertilizer
a
A new type of calculator is introduced to see if it is easier to use that the traditional calculator. Then students from a math class will be randomly selected to use the new calculator for the next chapter. Which of the following does not result in a simple random sample of 10 students fro all of the 38 students in a math class? a. Write the names of each student on equally sized poker chips. Put the chips in a bag, mix thoroughly , and draw out 10 chips. The names on the chips are the students that will use the new calculator b. Ask the students if they are good with technology and the first 10 students that say they are will be the ones tat use the new calculator c. Give each student a 2-digit number fro 01 to 38. Use a table of random digits and select two digits at a time until there are 10 number between 01 and 38. Ignore repeats and numbers larger than 38 d. Sample students from the class by numbering the students from 1 to 38 and using a random number generator to select 10 students. Be sure to ignore repeated numbers
a
Which of the following samples suffers from convenience sample? a. Sampling 50 students at random from a list of all 20,000 students at the high school and asking them the average about the time they spend on homework each night b. Sampling all students from each grade level and skiing them how much time they spend on extracurricular activities c. Sampling the first 100 student to arrive at the cafeteria for lunch and asking them if they like the food served at the cafeteria d. Sampling 5 students from a class by asking which students wants to go an after school meeting about the upcoming dance
c
A science teacher wanted to estimate the proportion of high school students that recycle bottles and cans. The science teacher made an announcement during the morning announcements asking students to come by his room to answer questions about recycling. The results showed that 75% of the students typically recycle bottles and cans. Which of the following best describes the sample? a. The sample is a voluntary response and will overestimate the true proportion of students that typically recycle bottles and cans b. The sample is a random sample and will overestimate the true proportion of student that typically recycle bottles and cans c. The sample is a random sample and the estimate should be close to the true proportion of students that typically recycle bottles and cans d. The sample is a convenience sample and will overestimate the true proportion of students that typically recycle bottles and cans
a
A telephone poll was conducted in a large area to determine if there was a relationship between income level and education level. Random cell phone numbers from the area were dialed and the income and education level of all the people called was recorded. The surveyed showed that the more education a person has, on average, the higher their income level. Which of the following is true about the relationship between income level and education level in this area? a. The relationship is questionable because the results are confounded with owning a cell phone b. The relationship is questionable because the results are affected by nonresponse c. The relationship is questionable because they did not call all cell phone numbers d. The survey had significant results so it seems that education level causes an increase in income level
a
An experiment is conducted to determine which type of window has the best insulation. A square room with four walls, each containing two windows, shown below, will be used to test the windows insulating ability, using a thermometer just behind the window. The sun rises east of the room and sets west of the room. There is also a large tree just north of the room, but nothing to the south. It is suggested that a block design, blocking by which direction the wall faces is used. Why is a block design preferable to a completely randomized design for this experiment? a. We should use a block design because it accounts for the variability in temperature due to the difference between the locations of the window in the room b. We should use the block design because it provides a baseline for comparing the differences in the two types of windows c. We should use a block design because it creates groups that are roughly equivalent at the beginning of the experiment d. We should use a block design because we must keep all other variable the same except for the type of window to prevent confounding
a
An experiment is conducted to see if advertisements affect the choice of snack a person eats. Twenty teenage volunteers are randomly assigned to watch a television program. One group of volunteers will watch the program with no ads and the other group will watch the same program, but with ads about healthily snack. After the program, the teenagers will be offered healthy and unhealthy snacks. Which of the following is not a benefit for having the program be the same except for whether or not the program has ads? a. Keeping the program the same helps confounding b. Keeping the program the same makes it easier to get statistically significant results if watching the ads is more effective at having teenagers choose healthy snacks than unhealthy snacks c. Keeping the program the same reduces variability in the number of volunteers that choose the healthy snacks compared to those that choose the unhealthy snacks d. Keeping the program the same eliminates the need for the random assignment
a
An experiment is designed to see if a new water repellant works better than the current one on the market for protecting shoes when it rains. You have 60 volunteers test which repellant is better. Which of the following describes a matched pairs design? a. Arrange the volunteers into two groups based on gender. Within each group, randomly assign half of the volunteers to receive shoes treated with the new repellant and half to receive shoes treated with the current repellant b. Arrange the volunteers into two groups based on hours of exercise per week. Within each group, randomly assign half of the volunteers to receive shoes treated with the new repellant and half to receive shoes treated with the current repellant c. Write the names of each equal sized pieces of paper and place them in a hat. Mix the papers throughly and draw out 30 different pieces of paper. Those thirty will receive shoes treated with the new repellant and the names not selected will receive shoes treated with the current repellant d. For each volunteer, randomly select either the right or left shoe and treat that shoe with the new repellant and treat the shoe not selected with current repellant
a
In order to estimate the mean time that students spend on homework each night, the principal at a school selected a random sample of the students enrolled in AP classes. The surveyed showed that on average, students spend 3 hours a night on homework. What potential bias is present in the design of this survey and what is the likely direction of the bias? a. The estimate is likely too large because of undercoverage and what is the likely direction of the bias? b. The estimate is likely too large because of nonrepose bias c. The estimate is likely too small because of nonrepose bias d. The estimate is likely too small because of undercoverage and what is the likely direction of the bias?
a
Shreya conducted a study to see if name-brand flashlight batteries last longer than generic batteries, on average. For each of 20 flashlights, she flipped a coin. If it was heads she used name-brand batteries and if it was tails she used the generic brand. She left the flashlights on and recorded how long it took for the batteries to wear out. The results showed that the flashlights that had the name-brand batteries, on average, lasted significantly longer that the flashlights that used the generic brand. What type of design is this study? a. This study is an example of a matched pairs experiment b. This study is an example of an observational study c. This study is an example of a simple random sample d. This study is an example of a completely randomized experiment
a
An experiment is conducted to see if advertisements affect the choice of snack a person eats. Twenty teenage volunteers are randomly assigned to watch a television program. One group of volunteers will watch the program with no ads and the other group will watch the same program, but with ads about healthily snack. After the program, the teenagers will be o freed healthy and unhealthy snacks. Which of the following should be done to randomly assign the subjects to treatment groups? a. Ask the teenager if they normally eat healthy snacks. The ones that do not are placed in the group that will watch the ads and the ones that do will be in the other group b. Assign each teenager a number from 1 to 20. Use a random number generator and pick ten different numbers from 1 to 20. The teenagers corresponding to the numbers will be in the first group and the remaining in the other group c. Let the teenagers pick which group they are in, because some of them like healthy snacks d. Make an alphabetized list of participants and place the first ten teenager in the first group and the remaining ten into the second group
b
The manager of an apartment complex wanted to estimate how long the dishwasher in the apartments would last before needing to be replaced. The apartment complex is made up of ten floors, each with ten apartments. The manager will randomly pick one floor of each apartment complex and have an appliance expert asses the condition of the dishwashers for each of the ten apartments. What type of sample did the manager perform? a. A simple random sample b. A cluster sample c. An experiment d. A stratified random sample
b
Two studies are described below. Determine if each study is an experiment or an observational study. Study 1: A doctor believes that patients who take vitamin C have less chance of getting sick. The doctor interviews a random sample of 60 of his patients and finds that 24 of them do not take vitamin C. The patients who take vitamin C, on average, were sick significantly less often than the patients that did not take vitamin C. Study 2: It is believed that pet ownership can reduce depression. To test this, a psychologist randomly selected 20 retirement homes where none of the residents owned a pet and interviewed a random sample of 35 resident from each community. It was determined that, on average, 21 of the 35 resident showed signs of depression. The psychologist then randomly selected ten of those communities and gave each community 12 cats and dogs for the residents to care for. Sic months later, the psychologist interviewed the same 35 rediseño from each community again and found, on average the communities that were given the cats and dogs had significantly less signs of depression than the communities that did not receive the cats and dogs. a. The first study described is an experiment and the second one is an observational study b. The first study described is an observational study and the second one is an experiment c. Both of the studies described are experiments d. Neither of the studies describes are experiments
b
An experiment is conducted to see if advertisements affect the choice of snack a person eats. Twenty teenage volunteers are randomly assigned to watch a television program. One group of volunteers will watch the program with no ads and the other group will watch the same program, but with ads about healthily snack. After the program, the teenagers will be o freed healthy and unhealthy snacks. Which of the following assignment of treatments will result in a completely randomized design? a. Alphabetize the teenagers and place the first ten names on the list in one group and the other ten in the other group. Flip a coin. I head, the first group watches the ads and if tails, the second group watches the ads b. Separate the teenagers into two groups, the ones that like healthy snacks and those that do not like healthy snacks. The group that does not like the healthy snacks will watch the ads c. Place each teenager name on equal size slips of paper. Put the papers in a hat and mix thoroughly. The first ten names selected are in the group that watches the ads and the other 10 do not watch the ads d. Allow the twenty teenagers to randomly choose which group they want to be in based on their preference
c
A newspaper conducts a poll online to determine what proportion of voters approves the proposed tax increase. In order to participate, people need to log onto the newspapers website. After 3 days, the newspaper reports that 78% of respondents are in favor of the tax increase. Which of the following is true about the sample proportion obtained from this sample? a. The sample is not biased and the sample proportion should be approximately the same as the actual proportion b. The sample is biased and overestimates the proportion because of convenience sampling c. The sample is biased and overestimates the proportion because of random sampling d. The sample is biased and overestimates the proportion because of voluntary response sampling
d
A study was conducted to determine if a doing homework help to increase test scores. A teacher asked 80 students if they complete their homework on a nightly basis. Forty of the students said yes and forty of the students said no. After collecting the data, it was determined that the students that completed the homework on a nightly basis, on average, had higher overall test grades that the students that did not complete homework on nightly basis. Does this study show that completing homework on a nightly basis helps increase test scores? a. Yes, because this is an observational study and the students that complete their homework on a nightly basis had higher test scores, on average b. No, the difference could not be from sample variability. More students need to be examined c. Yes, because the study describes a well designed experiment with a treatment group (students that complete homework nightly) and a control group (students that do not complete howework) d. No. Because this was an observational study the results might be confounded with overall study habits. Students that complete the homework regularly might also study more for the test
d
An experiment is conducted to determine which type of window has the best insulation. A square room with four wall, each containing two windows, shown below, will be used to test the windows insulating ability, using a thermometer just behind the window. The sun rises east of the room and sets west of the room. There is also a large tree just north of the room, but nothing to the south. Because there are two types of windows to be tested, the researcher will design and experiment that used blocking to determine which window has the best insulation. How should the block be formed? a. Created four blocks, each containing a window on the opposite side of the room, such window 3 and window 8. Because opposite sides are different, we want one window from each side of the room in each block. b. Create two blocks, the first block 2, 4, 6, and 8. Because each side has different conditions we want one window from each side in each block to see if there is an association. c. Create two blocks, the first block 3, 4, 7, 8 and the second block containing 1, 2, 5, 6. Because the east and west side deal with the sun they should be group together d. Created four blocks, with each side of the house as a block, such as windows 1 and 2 in a block. Because each side has different conditions it is reasonable to think that the side of the house is associated with temperature inside the window
d
An experiment was conducted to see if advertisements affect the choice of snack a person eats. Twenty teenage volunteers are randomly assigned to watch a television program. One group of volunteers will watch the program with no ads and the other group will watch the same program, but with ads about healthily snack. The proportion of teenagers choosing healthy snacks in the group that watched the program with the ads was larger that the proportion of teenagers choosing the healthy snack that watched the program without ads. and the difference was statistically significan What does it mean that the difference was statistically significant? a. The observed difference in the proportion of teenagers choosing healthy snacks in the two groups is so large that it is unlikely to occur only as a result of random assignment to groups, so the ads do not seem to affect the choice of snacks chosen to eat b. The observed difference in the proportion of teenagers choosing healthy snacks in the two groups was small enough to attribute to chance variation, so the ads do not seem to affect the choice of snacks chosen to eat c. The observed difference in the proportion of teenagers choosing healthy snacks in the two groups was small enough to attribute to chance variation, so the adds seem to affect the choice of snacks chosen to eat d. The observed difference in the proportion of teenagers choosing healthy snacks in the two groups is so large that it is unlikely to occur only as a result of random assignment to groups, so the ads seem to affect the choice of snacks chosen to eat
d
Mrs. Silavong has a classroom with 34 students and needs to select 5 students as representatives to serve on the principal's advisory board. In order to be fair, she decides to select a simple random sample using a table of random digits. She obtains a list of the students' names in alphabetical order and numbers the students according to their position on the list starting with 01 and continuing to 34. She used the following digits to find her random sample. 92310 67490 12065 42389 30114 57513 Which student's numbers correspond to those in her simple random sample? a. 23, 10, 01, 20, 30 b. 92, 31, 06, 74, 90 c. 31, 06, 12, 06, 23 d. 31, 06,12, 23, 30
d
