Exam 5: Experiments and Observational Studies

For Questions use the following narrative Narrative: BMD A recent magazine article stated that bone mineral density (BMD) may one day predict breast cancer risk in older women, according to a study in the Journal of the National Cancer Institute.Researchers followed the health of 8,905 women who were 65 or older and initially cancer free.Eventually 315 participants developed breast cancer.Women with the highest BMD were almost three times more likely to develop breast cancer, compared to the women with low BMD.(Better Homes and Gardens, October 2001, page 224.) -{BMD Narrative} Explain why it is not possible to conduct a randomized experiment in this situation.

If the experimental units as a group do not represent the intended population, the researcher cannot __________ the results from the experiment to the intended population.

Which type of observational study gives you better quality data, a retrospective study or a prospective study, and why?

Which of the following defines what is meant by a control group in an experiment?

One of the major advantages of an experiment over an observational study is that in an experiment, the researcher attempts to control for __________ variables.

A(n) __________ experiment is one in which neither the participant nor the researcher taking the measurements knows who had which treatment.

For Questions use the following narrative Narrative: Girls' grades A 1998 study by the Horatio Alger Association was summarized in USA Today by saying that high-school girls outperform boys in school.The article was titled "Study: Girls get higher grades" (USA Today 8/12/ 98).The study was based on a survey of 1,195 randomly chosen students aged 14-18.Among the findings: One third of the girls said they 'received mostly A's on their last report card' compared to only one-fifth of the boys.Three-fourths of girls 'believe they will have many opportunities available to them after they graduate' compared to only two-thirds of the boys. -{Girls' grades narrative} Do you think the conclusions of this study are justified? Why or why not?

Using 20 pairs of identical twins to participate in a study containing a treatment and a control is an example of what type of experimental design?

Without random sampling, which of the following can happen?

Which of the following statements about case-control studies is false?

One of the complications that can arise with observational studies is using the past as a source of data.This type of study is called a __________ study.

For Questions use the following narrative Narrative: Girls' grades A 1998 study by the Horatio Alger Association was summarized in USA Today by saying that high-school girls outperform boys in school.The article was titled "Study: Girls get higher grades" (USA Today 8/12/ 98).The study was based on a survey of 1,195 randomly chosen students aged 14-18.Among the findings: One third of the girls said they 'received mostly A's on their last report card' compared to only one-fifth of the boys.Three-fourths of girls 'believe they will have many opportunities available to them after they graduate' compared to only two-thirds of the boys. -{Girls' grades narrative} How would you change this study in order to improve the quality of the results?

What does randomization mean in terms of experiments?

Which of the following is implemented in an experiment to reduce unknown systematic biases due to confounding variables that might otherwise exist between treatment groups?

Random __________ is used to control for confounding variables and other possible sources of bias, allowing for the possibility of a cause and effect conclusion.

Discuss the biggest problem with using volunteers to participate in an experiment.

Which of the following statements is true?

In an experiment to see if a certain new drug can prevent a second heart attack, other drugs that the experimental units may or may not be taking already for heart related illnesses would be considered to be __________ variables.

Give two reasons why we must sometimes use an observational study instead of an experiment.

Which of the following describes an experiment?