Experiments and Observational Studies

What is the purpose of a sample survey?

• To examine existing data for a sample of individuals

• To record the behavior of animals in the wild

• To gather information about a population without disturbing the population

• To track the medical history of volunteers

What is the difference between retrospective and prospective observational studies?

• Retrospective studies attempt to influence the responses, while prospective studies observe individuals and measure variables of interest

• Retrospective studies observe individuals and measure variables of interest, while prospective studies attempt to influence the responses

• Retrospective studies track individuals into the future, while prospective studies examine existing data

• Retrospective studies examine existing data, while prospective studies track individuals into the future

What is the definition of an observational study?

• An observational study observes individuals and measures variables of interest but does not attempt to influence the responses

• An observational study observes individuals and measures variables of interest to influence the responses

• An observational study observes individuals and measures variables of interest to disturb the population

• An observational study observes individuals and measures variables of interest to gather information about a population

What is the definition of a response variable?

• A response variable does not measure an outcome of a study or help explain or predict changes in a response variable

• A response variable measures an outcome of a study

• A response variable measures an outcome of a study and helps explain or predict changes in a response variable

• A response variable helps explain or predict changes in a response variable

What is the definition of confounding?

• Confounding occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other

• Confounding occurs when two variables are not associated in such a way that their effects on a response variable can be distinguished from each other

• Confounding occurs when two variables are associated in such a way that their effects on a response variable can be distinguished from each other

• Confounding occurs when two variables are not associated in such a way that their effects on a response variable cannot be distinguished from each other

What is the purpose of a control group in an experiment?

• To provide a baseline for comparing the effects of other treatments

• To provide an inactive treatment for comparison

• To provide an active treatment for comparison

• To provide no treatment at all for comparison

What is the definition of the placebo effect?

• The placebo effect describes the fact that some subjects in an experiment will respond unfavorably to any treatment, even an inactive treatment

• The placebo effect describes the fact that all subjects in an experiment will respond unfavorably to any treatment, even an inactive treatment

• The placebo effect describes the fact that some subjects in an experiment will respond favorably to any treatment, even an inactive treatment

• The placebo effect describes the fact that all subjects in an experiment will respond favorably to any treatment, even an inactive treatment

What is the purpose of random assignment in an experiment?

• To create groups that are equivalent at the end of the experiment

• To create roughly equivalent groups at the beginning of the experiment

• To create groups that differ greatly at the beginning of the experiment

• To create groups that are not equivalent at the beginning of the experiment

What is the difference between a double-blind experiment and a single-blind experiment?

• In a double-blind experiment, neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is receiving. In a single-blind experiment, both the subjects and those who interact with them and measure the response variable know which treatment a subject is receiving

• In a double-blind experiment, both the subjects and those who interact with them and measure the response variable know which treatment a subject is receiving. In a single-blind experiment, neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is receiving

• In a double-blind experiment, either the subjects or the people who interact with them and measure the response variable don't know which treatment a subject is receiving. In a single-blind experiment, neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is receiving

• In a double-blind experiment, neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is receiving. In a single-blind experiment, either the subjects or the people who interact with them and measure the response variable don't know which treatment a subject is receiving

What is the purpose of random assignment in an experiment?

• To create groups that differ greatly at the beginning of the experiment

• To create groups that are not equivalent at the beginning of the experiment

• To create roughly equivalent groups at the beginning of the experiment

• To create groups that are equivalent at the end of the experiment