Section 1.2 Homework

1. What is an observational​ study? What is a designed​ experiment? Which allows the researcher to claim causation between an explanatory variable and a response​ variable?

What is an observational​ study?

1. An observational study measures the value of the response variable without attempting to influence the value of either the response or explanatory variables.
2. An observational study is when a researcher assigns individuals to a certain​ group, intentionally changing the value of an explanatory​ variable, and then recording the value of the response variable for each group.
3. An observational study is a list of all individuals in a population along with certain characteristics of each individual.

What is a designed​ experiment?

1. A designed experiment is a list of all individuals in a population along with certain characteristics of each individual.
2. A designed experiment is when a researcher assigns individuals to a certain​ group, intentionally changing the value of an explanatory​ variable, and then recording the value of the response variable for each group.
3. A designed experiment measures the value of the response variable without attempting to influence the value of either the response or explanatory variables.

Which allows the researcher to claim causation between an explanatory variable and a response​ variable?

_____________ allows the researcher to claim causation between an explanatory variable and a response variable

2.  What is a​ cross-sectional study? What is a​ case-control study? Which is the superior observational​ study? Why?

What is a​ cross-sectional study? Choose the correct answer below.

1. ​Cross-sectional studies are observational studies that collect information about individuals at a specific point in time or over a very short period of time.
2. ​Cross-sectional studies first identify a group of individuals to participate in the study. These individuals are then observed over a period of time. Over this period of​ time, characteristics about the individual are recorded.
3. ​Cross-sectional studies are observational studies that are​ retrospective, meaning that they require individuals to look back in time or require the researcher to look at existing records.
4. ​Cross-sectional studies are a list of all individuals in a population along with certain characteristics of each individual.

What is a​ case-control study? Choose the correct answer below.

1. ​Case-control studies are a list of all individuals in a population along with certain characteristics of each individual.
2. ​Case-control studies are observational studies that collect information about individuals at a specific point in time or over a very short period of time.
3. ​Case-control studies are observational studies that are​ retrospective, meaning that they require individuals to look back in time or require the researcher to look at existing records.
4. ​Case-control studies first identify a group of individuals to participate in the study. These individuals are then observed over a period of time. Over this period of​ time, characteristics about the individual are recorded.

Which is the superior observational​ study? Why? Choose the correct answer below.

1. ​Cross-sectional studies are always the superior observational study because they are cheap and quick to do.
2. ​Case-control studies are always the superior observational study because they are relatively inexpensive to conduct and can be done relatively quickly.
3. Neither study is always the superior to the other. Both have advantages and disadvantages that depend on the situation.

3.  Determine whether the study depicts an observational study or an experiment.  A study is conducted to determine if there is a relationship between colon cancer and fat consumption. Patients with colon cancer are asked about their fat consumption.

Does the description correspond to an observational study or an​ experiment?

1. The study is an experiment because the study examines individuals in a​ sample, but does not try to influence the variable of interest.
2. The study is an observational study because the researchers control one variable to determine the effect on the response variable.
3. The study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable.
4. The study is an experiment because the researchers control one variable to determine

4.  Researchers wanted to determine if having a supply of sugary snacks in the bedroom is associated with obesity. The researchers administered a questionnaire to 393 ​twelve-year-old adolescents. After analyzing the​ results, the researchers determined that the body mass index of the adolescents who had a

supply of sugary snacks in their bedroom was significantly higher than that of the adolescents who did not have a supply of sugary snacks in their bedroom. Complete parts​ (a) through​ (e) below.

​(a) Why is this an observational​ study? What type of observational study is​ this?

Why is this an observational​ study?

1. The researchers administered a questionnaire to obtain their data without trying to influence an explanatory variable of the study.
2. The researchers observed the behavior of the individuals in the study without trying to influence an explanatory variable of the study.
3. The researchers tried to influence the outcome of the study.
4. The researchers intentionally changed an explanatory variable of the study.

What type of observational study is​ this?

1. Cohort study
2. Case-control study
3. ​Cross-sectional study

​(b) What is the response variable in the​ study? Is the response variable qualitative or​ quantitative? What is the explanatory​ variable?

What is the response variable in the​ study? Is the response variable qualitative or​ quantitative?

1. The response variable is the number of the adolescents who participate in the study. The response variable is quantitative.
2. The response variable is the number of the adolescents who have a supply of sugary snacks in their bedroom. The response variable is quantitative.
3. The response variable is whether the adolescent has a supply of sugary snacks in the bedroom or not. The response variable is qualitative.
4. The response variable is the body mass index of the adolescents. The response variable is quantitative.

What is the explanatory​ variable?

1. The explanatory variable is whether the adolescent has a supply of sugary snacks in the bedroom or not.
2. The explanatory variable is the body mass index of the adolescents.
3. The explanatory variable is the number of the adolescents who participate in the study.
4. The explanatory variable is the number of the adolescents who have a supply of sugary snacksin their bedroom.

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(c) Can you think of any lurking variables that may affect the results of the​ study?

1. Yes. For​ example, possible lurking variables might be drinking habits and the amount of exercise per week.
2. No, there are no lurking variables in this study.
3. Yes. For​ example, a possible lurking variable might be the age of the individual.
4. There is not enough information to answer this question.

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(d) In the​ report, the researchers​ stated, “These results remain significant after adjustment for socioeconomic​ status.” What does this​ mean?

1. It means that socioeconomic status is not an explanatory variable and that including this variable in the study does not change the results of the study.
2. The researchers made an effort to avoid confounding by accounting for potential lurking variables.
3. It means that when the results are separated by socioeconomic​ status, there are significant differences between each socioeconomic status.
4. It means that socioeconomic status is an explanatory variable and that including this variable in the study changes the results of the study.

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(e) Does a supply of sugary snacks in the bedroom cause a higher body mass​ index? Explain.

1. No. It can only be said that a supply of sugary snacks in the bedroom and obesity are associated because the body mass index of the adolescents who had a supply of sugary snacks in their bedroom was significantly higher than that of the adolescents who did not have a supply of sugary snacks in their bedroom.
2. Yes. A supply of sugary snacks in the bedroom causes obesity because the body mass index of the adolescents who had a supply of sugary snacks in their bedroom was significantly higher than that of the adolescents who did not have a supply of sugary snacks in their bedroom.
3. No. The results state that a supply of sugary snacks in the bedroom causes a higher body mass index for​ twelve-year-old adolescents, but the conclusion cannot be made that it causes a high body mass index for all people.
4. Yes. A supply of sugary snacks in the bedroom is associated with obesity because the body mass index of the adolescents who had a supply of sugary snacks in their bedroom was significantly higher than that of the adolescents who did not have a supply of sugary snacks in their bedroom.

5.  A web page design firm has two designs for an online hardware store. To determine which is the more effective​ design, the firm uses one page when on a mobile platform and a second page when on a desktop. For each​ visit, the firm records the visitor’s rating on the layout and the number of items viewed. Complete parts​ (a) through​ (c) below.

​(a) What is the explanatory variable in this​ study? Is it qualitative or​ quantitative?

1. The explanatory variable is the web page design. The explanatory variable is qualitative.
2. The explanatory variable is the number of items viewed. This explanatory variable is quantitative.
3. The explanatory variable is the viewing device. This explanatory variable is qualitative.
4. The explanatory variable is the visitor’s rating on the layout. This explanatory variable is qualitative.

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(b) What are the two response​ variables? For each response​ variable, state whether it is qualitative or quantitative. Select all that apply.

1. One response variable is the visitor’s rating on the layout. This response variable is qualitative.
2. One response variable is the number of items viewed. This response variable is quantitative.
3. One response variable is the viewing device. This response variable is qualitative.
4. One response variable is the web page design. This response variable is qualitative.

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(c) Explain how confounding might be an issue with this study. Choose the correct answer below.

1. Since there is only one explanatory​ variable, and two response​ variables, the explanatory variable will not affect both response variables​ equally, resulting in misleading results.
2. Since the designs are being tested with two different viewing devices​, preferences depending on the viewing device may affect the response variables for those groups.
3. Since the variables are not all quantitative or all​ qualitative, they may​ interact, causing the results to be misleading or incorrect.
4. Since there are two response variables in this​ study, they may​ interact, causing the results to be misleading or incorrect.

6.   Select the correct choices that complete the sentence below.

In statistical​ studies, researchers want to determine how varying one or more​ _______ variables may impact the value of​ a(n) _______ variable.

​(This is a reading assessment question. Be certain of your answer because you only get one attempt on this​ question.)

In statistical​ studies, researchers want to determine how varying one or more ______ variables may impact the value of​ a(n) _____ variable.