Exam 5: Experiments and Observational Studies

Discuss the main difference between a case-control study and a matched-pairs experiment (other than the fact that one is an observational study and one is an experiment).

In order to establish a connection between an explanatory and response variable in an observational study, what is needed?

Which of the following is not true about placebos?

A(n) __________ variable is one that attempts to explain or is purported to cause (at least partially) differences in a(n) __________ variable.

Give an example of an experiment in which it would be unethical to give the control group a placebo.

An observational study that follows a group of high school students into the future, recording how many children they have (if any) and at what age(s) they had those children is an example of a(n) __________ study.

Without random assignment, which of the following can happen?

A common mistake made by the media, the general public, and some researchers, is to think that a link between two variables in any study implies that one variable causes the other.Explain what is wrong with this automatic conclusion.

Which of the following is a potential complication of observational studies?

One of the complications that can arise with observational studies is __________ variables and the implications of causation.

For Questions use the following narrative Narrative: Toy colors Suppose a toy company wants to know if certain colors are more appealing and attractive to toddlers than others.They decide to measure this by choosing five colors of blocks and making sets of blocks in each of the five colors.Then they found 30 toddlers to participate in the study, and they randomly assigned each toddler a block color.They observed each toddler separately at the same time of the day, and gave them no other toys to play with.They recorded the length of time each toddler played with the blocks, to see if some colors of blocks were played with longer than other colors.All toddlers in the experiment were the same age (2 years old) and an equal number of girls and boys played with each color of blocks. -{Toy colors narrative} What is the explanatory variable and what is the response variable?

How can a researcher try to address the problem of confounding variables when designing an observational study?

The case-control design has some clear advantages over randomized experiments as well as over other observational studies.Name two of those advantages.

Which of the following is a potential complication of a poorly designed/conducted experiment?

Suppose you come across an experiment or observational study in which a random sample was not used.To what extent can (should) the results be extended to a larger population?

Suppose you come across an experiment in which random assignment was not used.To what extent will the conclusions of the experiment be affected?

It is the purpose of what type of study to find out whether one or more explanatory variables are related to a certain disease (for example whether smoking causes lung cancer)?

Which of the following is implemented in an experiment to reduce known sources of natural variability in the response variable, so that differences due to the explanatory variable can be detected more easily?

Which of the following studies can result in researchers extending the results inappropriately because the sample doesn't represent the intended population?

What is the main purpose of using a random sample in a study?