Exam 1 - HW 3

In a classroom of 25 first graders, 75% can write their names clearly. Suppose we selected 10 children from the class and asked them to write their names. Of this group, 60% could do this successfully. Determine whether the following statement is true or false. The 10 children selected would make up the sample.

True

Michelin wants to test a new type of radial tire, so researchers design a study in which they randomly assign the new tires to two of the four wheels of a car and use the current model of tires on the other two wheels. They repeat this over multiple cars, drive them a fixed number of miles, and then measure the wear on both the old and new versions of the tires and compare them. Determine whether the following statement is true or false. Michelin has set up an experiment.

True

A local health fair vendor attempts to get people to complete a survey on health and fitness habits. She calls out to people as they pass by asking them if they would like to participate in a survey. Many people ignore the calls as they pass by. This technique will introduce what type of bias? nonresponse bias response bias selection bias no bias is being introduced

nonresponse bias

What type of bias occurs when responses are not obtained from all individuals selected for the sample? nonresponse bias response bias selection bias no bias is being introduced

nonresponse bias

A survey presented by Stage of Life in August 2012 was used to determine the preferred music genres of the average U.S. teenage Internet user. If they could listen to only one genre of music for the rest of their lives, 15.3% of respondents stated they would choose country music.† (a) This survey is an example of which of the following? experiment observational study

observational study

A record store owner is interested in the average length of song on the albums in his store. He decides to break his store into category of music and take a simple random sample within each category. The owner looks at each genre and realizes that there are 10 categories of music. He wants to sample 100 total albums. How many albums should he sample from each genre if he wants an equal representation of each music category?

10 albums per genre

In recent years, more and more people are turning to the Internet for advice on their health. As a biomedical student, you want to know how well the people in different age-groups trust the advice found online. You have 48 family members who are willing to be surveyed, and they are in 4 different age-groups with 12 members in each group. If you want to have a total of 12 family members in your health poll, how many should you choose from each age-group? ______ family members per strata

3

Statistics is used in which of the following industries? Advertising Entertainment Health care Marketing Politics Transportation Sports All of the above None of the above

All of the above

Which of the following is a key to completely randomized design? All subjects are randomly blinded. All subjects are randomly selected from the population. All researchers are randomly assigned to subjects. All subjects are randomly assigned to treatments.

All subjects are randomly assigned to treatments.

What is the first step in the statistical research process? Ask Good Questions Analyze and Interpret Data Clean Data Organize and Present Results Collect Data

Ask Good Questions

A basketball coach is interested in determining if shooting free throws underhand is better than shooting them using the overhead method. He has four high school teams (two boys' teams and two girls' teams, with 13 players on each team) available to take part in an experiment. He believes that the difference in shooting percentages will vary more for boys than for girls. He randomly chooses and instructs half of the boys to continue shooting free throws overhead and the rest of the boys to shoot underhand. He does the same for the girls. At the end of a six-game summer league, he compares the shooting percentages for the overhead shooting boys to the underhand shooting boys and the overhead shooting girls to the underhand shooting girls. What is the advantage of using a block design for this study? Blocking will provide more precise results by using one group as a control group (overhead shooting), another group as the treatment group (underhand shooting). Blocking by gender will increase the variation in the response variable by introducing a new variable into the experimental design: gender. Blocking by gender will reduce the variation in the response variable by creating homogeneou

Blocking by gender will reduce the variation in the response variable by creating homogeneous groups and determining the effect of the new shooting style on the response (percentage of made shots) separately for each block (gender).

The career coach in the video speaks about and demonstrates effective strategies for asking for a raise. Which of the following is not one of these strategies? Don't ask for more than you're expecting because you will come across as greedy. Ask for more than you're expecting to leave room for negotiation. Emphasize what you do that brings more money into the organization. Try to project confidence as you ask for a raise.

Don't ask for more than you're expecting because you will come across as greedy.

A basketball coach is interested in determining if shooting free throws underhand is better than shooting them using the overhead method. He has four high school teams (two boys' teams and two girls' teams, with 13 players on each team) available to take part in an experiment. He believes that the difference in shooting percentages will vary more for boys than for girls. He randomly chooses and instructs half of the boys to continue shooting free throws overhead and the rest of the boys to shoot underhand. He does the same for the girls. At the end of a six-game summer league, he compares the shooting percentages for the overhead shooting boys to the underhand shooting boys and the overhead shooting girls to the underhand shooting girls. Determine whether the following statement is true or false. This experimental design can be implemented as a double-blind experiment.

False

A marketing company is interested in determining which spouse is primarily responsible for doing the shopping for the family. One thousand four hundred randomly selected shoppers from all grocery stores in the state of Florida were questioned. Those individuals were asked to estimate the proportion of time they do the grocery shopping for their family. Determine whether the following statement is true or false. The population of interest in this study is the 1,400 randomly selected shoppers from all grocery stores in the state of Florida that were questioned.

False

Determine whether the following statements are true or false. A pollster goes door-to-door during the day to determine what percentage of households watch soap operas. The pollster would be able to obtain responses only from those who are home during the day. This is an example of nonresponse bias.

False

In a classroom of 25 first graders, 75% can write their names clearly. Suppose we selected 10 children from the class and asked them to write their names. Of this group, 60% could do this successfully. Determine whether the following statement is true or false. The value, 60%, is a parameter.

False

In an effort to reduce the number of injuries on playgrounds, a city council considers a new design of monkey bars for public parks. One hundred children volunteer to take part in a study comparing the new design to the old design. They are randomly assigned to a set of monkey bars to play on. As it turns out, of the 50 assigned to the new design, 46 of the children are boys, while 38 of the children assigned to the old equipment are girls. Determine whether the following statement is true or false. This experimental design can be implemented as a double-blind experiment.

False

It is important to have very strong math skills in order to be successful in a statistics course. T or F?

False

Tim Tebow was named the Florida Gators' starting quarterback for the 2007 season. That season he averaged 4.3 yards per carry on the ground.† Determine whether the following statement is true or false. The number 2007 is a parameter.

False

A dean of residential life wonders if students who live on the top floor of a large dormitory are absent from classes more frequently than students who live on the bottom floor. When students apply to live in the dorm, the dean asks them which floor they would like to live on. The dean randomly selects 15 students who applied for the top floor and 15 students who applied for the bottom floor to be in the experiment. The dean then checks to see if the 15 students who applied and were placed on the top floor were absent more frequently than the 15 students who applied for and were placed on the bottom floor. Has the dean properly used a completely randomized design? Yes. Students were randomly selected from those who wished to live on the floors in question. No. Students were not randomly selected to live in the dorm. No. Students should be randomly assigned to classes that start at different times. No. Students should have been randomly assigned to floors and then had their absence rate checked as the year went on.

No. Students should have been randomly assigned to floors and then had their absence rate checked as the year went on.

The video cites the statistic that "the average pay rise across major US employers this year" is 3%. Which of the following methods of calculating this statistic is both feasible and likely to be reasonably accurate? Obtain a representative sample of employees of major US employers and ask each to report the amount of their raise this year. Ask all major US employers the average raise they granted this year. Ask all employees of all major US employers the amount of their raise this year. Ask an employment expert such as the one shown in the video to estimate the average pay rise across major US employers this year.

Obtain a representative sample of employees of major US employers and ask each to report the amount of their raise this year.

A record store owner is interested in the average length of song on the albums in his store. He decides to break his store into category of music and take a simple random sample within each category. Why would the record store owner decide to use a stratified random sample over other sampling techniques? The lengths of some songs are inherently longer in specific music types. For example, rap songs tend be shorter than classic rock songs. There are too many records to effectively take a simple random sample. He wants to sample from only 1 genre. He likes certain genres better than others.

The lengths of some songs are inherently longer in specific music types. For example, rap songs tend be shorter than classic rock songs.

A basketball coach is interested in determining if shooting free throws underhand is better than shooting them using the overhead method. He has four high school teams (two boys' teams and two girls' teams, with 13 players on each team) available to take part in an experiment. He believes that the difference in shooting percentages will vary more for boys than for girls. He randomly chooses and instructs half of the boys to continue shooting free throws overhead and the rest of the boys to shoot underhand. He does the same for the girls. At the end of a six-game summer league, he compares the shooting percentages for the overhead shooting boys to the underhand shooting boys and the overhead shooting girls to the underhand shooting girls. Which method is an example of how randomization could be implemented within this study? - Each of the boys should be allowed to choose which style they want to use for the games. The same should be done with the girls. - The best free-throw shooters should be assigned to the underhand method and the worst shooters should be assigned to the overhead style. - The researcher should give all of the boys a coin to flip. Those boys that flip heads are instr

The researcher should give all of the boys a coin to flip. Those boys that flip heads are instructed to shoot underhand and those who flipped tails are assigned to the overhead style. The same procedure is used with the girls.

The video presents what it calls an experiment in which a man and a woman simulate asking for a raise. Typically, in an "experiment" or "statistical study" researchers care about drawing conclusions for a well-defined group of people, such as "all women in the workforce in the US" or "all babies in their first year of life." This well-defined group is called the population. Since typically researchers cannot reach all members of a population, they assess a subset of this population, called a sample. In the experiment in the video, who is/are the sample(s) and who is/are the population(s)? There are two samples and two populations: the samples are all working men and all working women and the populations are the man and woman shown asking for a raise. The sample is all working people and the population is the man and woman shown asking for a raise. There are two samples and two populations: the samples are the man and woman shown asking for a raise and the populations are all working men and all working women.

There are two samples and two populations: the samples are the man and woman shown asking for a raise and the populations are all working men and all working women.

A local health fair vendor attempts to get people to complete a survey on health and fitness habits. She calls out to people as they pass by asking them if they would like to participate in a survey. Many people ignore the calls as they pass by. Determine whether the following statement is true or false. In this scenario, the sample consists of 80 people who agreed to complete the survey.

True

The per capita consumption of bottled water in the United States amounted to 27.6 gallons in 2009. Bottled water is drinking water (carbonated or still) sold in plastic or glass water bottles. Per capita consumption of bottled water in the United States has continued to steadily increase. In 2012, it amounted to 30.8 gallons. In 2015, the per capita consumption was 36.5 gallons.† Determine whether the following statement is true or false. If randomly selected individuals were asked how much bottled water they consumed in a year, the resulting data would be numerical

True

In an effort to reduce the number of injuries on playgrounds, a city council considers a new design of monkey bars for public parks. One hundred children volunteer to take part in a study comparing the new design to the old design. They are randomly assigned to a set of monkey bars to play on. As it turns out, of the 50 assigned to the new design, 46 of the children are boys, while 38 of the children assigned to the old equipment are girls. (a) Is this a completely randomized design? Yes, because all children were randomly assigned to one of the two treatments. Yes, because accidents are random occurrences. No, because the groups on each set of bars need to be either all boys or all girls. No, because boys and girls were not assigned evenly to each set of monkey bars.

Yes, because all children were randomly assigned to one of the two treatments.

To prevent the loss of crops to crows, a new form of scarecrow is developed. There are 281 farms in the area that have more than 100 acres of land. Sixty-two farms volunteer for this experiment. Thirty-one are randomly selected to receive the new scarecrow. The percentage of crop lost to crows is compared from last year (without the new scarecrow) to this year between all 62 farms. Is this a completely randomized design? Yes, because the 62 farms are randomly selected for placement in the two treatments. Yes, because the crows will eat the crops randomly rather than accept any assignment to a specific farm. No, because not all 281 farms were used in the experiment. No, because the crops were not randomly allocated to the various farms.

Yes, because the 62 farms are randomly selected for placement in the two treatments.

In an effort to reduce the number of injuries on playgrounds, a city council considers a new design of monkey bars for public parks. One hundred children volunteer to take part in a study comparing the new design to the old design. They are randomly assigned to a set of monkey bars to play on. As it turns out, of the 50 assigned to the new design, 46 of the children are boys, while 38 of the children assigned to the old equipment are girls. In this scenario, is gender a confounding variable? Yes. Because there was no time limit placed on the amount of play, more injuries might occur on one set of monkey bars because the children are there longer. Yes. Gender is a confounding variable because we may not be able to tell if the difference in injury rate is because of the equipment or the gender of the children playing on the monkey bars. No. Each boy should be allowed to choose which monkey bars he wants to play on. The same should be done with each girl. No. The researcher should flip a coin to decide which boys will play on the new monkey bars and which on the old. The same should be done to decide which girls will play on which monkey bars.

Yes. Gender is a confounding variable because we may not be able to tell if the difference in injury rate is because of the equipment or the gender of the children playing on the monkey bars.

To prevent the loss of crops to crows, a new form of scarecrow is developed. There are 281 farms in the area that have more than 100 acres of land. Sixty-two farms volunteer for this experiment. Thirty-one are randomly selected to receive the new scarecrow. The percentage of crop lost to crows is compared from last year (without the new scarecrow) to this year between all 62 farms. (a) What are the subjects in this scenario? farms crops scarecrows crows

farms

In a classroom of 25 first graders, 75% can write their names clearly. (a) The number 75% is which of the following? sample statistic parameter population

parameter

The per capita consumption of bottled water in the United States amounted to 27.6 gallons in 2009. Bottled water is drinking water (carbonated or still) sold in plastic or glass water bottles. Per capita consumption of bottled water in the United States has continued to steadily increase. In 2012, it amounted to 30.8 gallons. In 2015, the per capita consumption was 36.5 gallons.† (a) The per capita consumption of bottled water in the United States is which of the following? biased statistic categorical variable numerical variable parameter

parameter

Tim Tebow was named the Florida Gators' starting quarterback for the 2007 season. That season he averaged 4.3 yards per carry on the ground.† (a) The number 4.3 is which of the following? sample statistic parameter population

parameter

In a classroom of 25 first graders, 75% can write their names clearly. "All students in the classroom" is a description of which of the following? sample statistic parameter population

population

A local health fair vendor attempts to get people to complete a survey on health and fitness habits. She calls out to people as they pass by asking them if they would like to participate in a survey. Many people ignore the calls as they pass by. Suppose that 80 people agreed to complete the survey. The survey is being administered verbally by a health and fitness instructor at a local gym. She asks every person who agreed to complete the survey how many times each week they exercise. The fact that this survey is being administered by a health and fitness instructor at a local gym would likely lead to what type of bias? nonresponse bias response bias selection bias no bias is being introduced

response bias

It seems reasonable that high school seniors may have greater financial needs than do high school juniors. For example, seniors have greater expenses such as senior trips and preparing for college. Therefore, one question we might like to answer is "Do seniors work more hours for pay than juniors?" Jennifer, a senior at a particular high school, randomly collected the following data (measured in hours worked for pay per week). The 20 juniors questioned are the __________ and all juniors at the particular high school are the ____________

sample; population

Which of the following are types of bias? (Select all that apply.) sample size bias selection bias response bias nonresponse bias

selection bias response bias nonresponse bias

A large college is undergoing massive construction for updates and new buildings. Because of this, there will be limited parking for the next 2 years. University administration must survey the students in order to predict how many parking spaces should be reserved for each class (freshmen, sophomores, juniors, and seniors). Once the population is stratified, they must now take a _____________ simple random complex random system sample within each group to complete the survey.

simple random

A ______ is a number that describes a sample

statistic

A survey presented by Stage of Life in August 2012 was used to determine the preferred music genres of the average U.S. teenage Internet user. If they could listen to only one genre of music for the rest of their lives, 15.3% of respondents stated they would choose country music.† The number 15.3% is which of the following? parameter population sample statistic

statistic

A record store owner is interested in the average length of song on the albums in his store. He decides to break his store into category of music and take a simple random sample within each category. (a) The name for this type of sampling method is ______ sampling

stratified random

A large college is undergoing massive construction for updates and new buildings. Because of this, there will be limited parking for the next 2 years. University administration must survey the students in order to predict how many parking spaces should be reserved for each class (freshmen, sophomores, juniors, and seniors). (a) Which of the following should the administration consider to be the strata? university classes construction sites parking spaces faculty members

university classes