Homework Section 1.2

What is the explanatory variable to question 14? - the explanatory variable is the number of the adolescents that participate in the study. - the explanatory variable is whether the adolescent has a TV in the bedroom or not. - the explanatory variable is the body mass index of the adolescents

- the explanatory variable is whether the adolescent has a TV in the bedroom or not.

In the​ report, the researchers​ stated, "These results remain significant after adjustment for socioeconomic​ status." What does this​ mean? - the researchers made an effort to avoid confounding by accounting for potential lurking variables. - it means that socioeconomic status is an explanatory variable and that including this variable in the study changes the results of the study. - 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.

- the researchers made an effort to avoid confounding by accounting for potential lurking variables.

What is a cohort study?

A cohort study first identifies a group of individuals to participate in the study​ (the cohort). The cohort is then observed over a period of time​ (sometimes a long period of​ time). Over this time​ period, characteristics about the individuals are recorded and some individuals in the study will be exposed to certain factors​ (not intentionally) and others will not. At the end of the study the value of the response variable is recorded for the individuals.

What is a designed experiement? - a designed experiment measures the value of the response variable without attempting to influence the value of either the response or explanatory variables. - a designed experiment is a list of all individuals in a population along with certain characteristics of each individual. - a designed experiment is when a researches assigns individuals to a group, intentially changing the value of an explanatory variable, and then recording the value of the response variable for each group.

a designed experiemtn is when a researcher assigns individuals to a group, intentially changing the value of an explanatory variable, and then recording the value of the response variable for each group.

What is a case-control study?

a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute

What is a cross-sectional study?

a type of observational study that analyzes data from a population, or a representative subset, at a specific point in time

What is an observational study? - an observational study measures the value of the response variable without attempting to influence the value of either the response or explanatory variables. - an observational study is a list of all individuals in a population along with certain characteristics of each individual. - an observational study is when a researches 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.

an observational study 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? - designed experiment - observational experiment

designed experiment

​Does a television in the bedroom cause a higher body mass​ index? - no, a television in the bedroom and obesity are associated because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. - yes, a television in the bedroom causes obesity because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. - no, a television in the bedroom does not cause obesity because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom

no, a television in the bedroom and obesity are associated because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom.

What is the explanatory variable? - the explanatory variable is whether the woman has non-melanoma skin cancer or not. - the explanatory variable is consumption of caffeinated coffee. - the explanatory variable is the number of individuals that participate in the study.

the explanatory variable is consumption of caffeinated coffee.

In their​ report, the researchers stated that​ "After adjusting for various demographic and lifestyle​ variables, daily consumption of six or more cups was associated with a​ 30% reduced prevalence of nonmelanoma skin​ cancer." Why was it important to adjust for these​ variables? - the researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variables that were not considered in a​ study, but that affect the value of the response variable. - it is not important to adjust for explanatory variables. - the researchers were sure that various demographic and lifestyle variables had greater influence than daily consumption of six or more cups.

the researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variables that were not considered in a​ study, but that affect the value of the response variable.

What is the response variable in the study to question 14? - the response variable is the body mass index of the adolescents. - the response variable is whether the adolescent has a TV in the bedroom or not. - the response variable is the number of the adolescents that participate in the study.

the response variable is the body mass index of the adolescents

What is the response variable in the study from question 7? - the response variable is whether the woman has non-melanoma skin cancer or not. - the response variable is the number of individuals that participate in the study. - the response variable is the consumption of caffeinated coffee.

the response variable is whether the woman has nonmelanoma skin cancer or not.

Determine whether the study depicts an observational study or an experiment: "eighty patients with stomach cancer are divided into two groups. One group receives an experimental drug to fight cancer, the other a placebo. After one year, the spread of the cancer is measured." - the study is an observational study because the researchers control one variable to determine the effect on the response variable. - the study is an experiment because the researchers control one variable to determine the effect on the response variable - the study is an obervational study because the study examines individuals in a sample, but does not try to influence the response variable. - the study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest.

the study is an experiment because the researchers control one variable to determine the effect on the response variable.

Determine whether the study depicts an observational study or an experiment: "While shopping, 400 people are asked to perform a taste test in which they eat two brands of candies. They are then asked which candy they prefer." - the study is an observational study because the researchers control one variable to determine the effect on the response variable. - the study is an observational study because the study examines individuals in a sample, but does not try to influence the variable of interest. - the study is an experiment because the researchers control one variable to determine the effect on the response variable. - the study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest.

the study is an observational study becasue the study examines individuals in a sample, but does not try to influence the variable of interest.

Determine whether the study depicts an observational study or an experiment: "A poll is conducted by a school's English department in which ninth-grade students are asked if they prefer to be in their English class or their science class." - the study is an experiment because the researchers control one variable to determine the effect on the response variable. - the study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest. - the study is an observational study becasue the researchers control one variable to determine the effect on the response variable. - the study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable.

the study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable.

Researchers wanted to determine if having a television​ (TV) in the bedroom is associated with obesity. The researchers administered a questionnaire to 371 ​twelve-year-old adolescents. After analyzing the​ results, the researchers determined that the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. Why is this an observational study? - this is an observational study because the researchers try to influence the outcome of the study. - this is an observational study because the researchers observe the behavior of the individuals in the study without trying to influence an explanatory variable of the study. - it is not an observational study.

this is an observational study because the researchers observe the behavior of the individuals in the study without trying to influence an explanatory variable of the study.

"Researchers wanted to determine if there was an association between daily coffee consumption and the occurrence of skin cancer. The researchers looked at 93,907 women and asked them to report their​ coffee-drinking habits. The researchers also determined which of the women had non-melanoma skin cancer. After their​ analysis, the researchers concluded that consumption of six or more cups of caffeinated coffee per day was associated with a reduction in nonmelanoma skin cancer." What type of observational study was this? - this was a cross-sectional study because all information about the individuals was collected at a specific point in time. - this was a case-control study because individuals that had a certain characteristic were matched with those that did not. - this was a cohort study because it identified a group of individuals to participate in the study and observed the group over a period of time.

this was a cross-sectional study because all information about the indivduals was collected at a specific point in time.

Can you think of any lurking variables that may affect the results of the​ study? - there is not enough information to answer this question. - yes. For​ example, possible lurking variables might be eating habits and the amount of exercise per week. - no, there are no lurking variables in this study.

yes. For​ example, possible lurking variables might be eating habits and the amount of exercise per week.