A researcher randomly assigned boys and girls to each of two groups. One group was assigned to watch a violent television program while the other group watched a nonviolent program. The children's behavior was then recorded for incidences of aggressive behavior. This research method is best characterized as...

Dr. Larson was interested in whether classical music helps students perform better on a test. Dr. Larson randomly assigned half of the study's participants to a group that listened to classical music while taking a test. The other half of the participants did not listen to music while taking a test. The research design Dr. Larson used is...

Jane Goodall lived among wild chimpanzees intermittently for decades, studying their social and family systems while keeping her interaction with the chimpanzees to a minimum. Her research method can most accurately be described as a...

A psychologist designed a study to test the effects of cell phone use on driving safety. Participants were randomly assigned either to drive an automobile simulator while talking to a friend on a cell phone or to drive a simulator without talking on a phone.

Which type of research does the scenario describe?

To test the effects of eating breakfast on test grades. I randomly select half of my students and feed them breakfast while giving the other half nothing to eat. I then give them all a test and compare the test grades of each group.

Is this an experiment or an observational study?

Researchers were interested to know whether internal vehicle temperatures vary by outside temperatures. To evaluate this, temperature rise was measured continuously over a 60-minute period in a dark SUV on 16 different clear, sunny days with outside temperatures ranging from 72^oF to 96^oF. The researchers' method of analysis is best described as:

Identify each of the following as an observational study or an experiment.

Compare the grades on a final math test of 25 students who were given a calculator to use and 25 students who do not use calculators.