Experimental vs Observational Studies

For many years automobile insurance companies have charged young men higher premiums, reflecting this group’s relatively poor driving record. An executive in the insurance industry believes that different premiums should be charged according to age for all drivers, because drivers in some age groups drive considerably more than others. To examine this issue, 50 young (25- to 40-year olds), 50 middle-age (40- to 55-year-olds), and 50 older (over 55-years-old) drivers were questioned concerning the number of miles they drove in the previous 12 months.

• Experiment

• Observational Study

Researchers wanted to know if there is a link between proximity to high-tension wires and the rate of leukemia in children. To conduct the study, researchers compared the rate of leukemia for children who lived within 1/2 mile of high-tension wires to the rate of leukemia for children who did not live within 1/2 mile of high-tension wires.

• Observational Study

• Experiment

You want to see if students who have a 4.0 grade point average study more than those who do not.

• experiment

• observational study

You want to compare the health of students who walk to school to the health of students who ride the bus

• experiment

• observational study

Decide if the scenario would be EXPERIMENTAL or OBSERVATIONAL. Compare the grades on a final math test of 25 students who use calculators and 25 students who do not use calculators. The students decide which group they are in. This represents a ​ (a)   study.

• Experimental

• Observational

In an ________________, a researcher observes and measures characteristics of interest of part of the population but does not change existing conditions.

• Experiment

• Observational Study

To test the effects of breakfast on grades I ask my students if they ate breakfast and then compare the breakfast eaters grades to the non-breakfast eaters. This is an example of:

• Observational study

• Experiment

Rats with cancer are divided into two groups. One group receives 5 milligrams of a medication that is thought to fight cancer and the other receives 10 mg. After 2 years, the spread of cancer is measured.

• Observational Study

• Experiment

Which is one of the main differences between experiments and observational studies?

• There is a response variable in an experiment, but not in an observational study.

• There is at least one explanatory variable in an experiment, but not in an observational study.

• An experiment requires blocking, while an observational study does not.

• An experiment can be used to establish a causal relationship, but an observational study cannot.

• Observational studies require larger samples than experiments.