Surveys, Observational Studies and Experiments

Determine whether the situation is an experiment or observational study.

A researcher asks students the average number of hours of sleep they get per night and examines whether the amount of sleep affects students' grades.

Determine whether the situation is an experiment or observational study.

A park employee wants to know if latex paint is more durable than non-latex paint.  She paints 50 benches with latex paint and 50 with non-latex paint.

Four groups of randomly selected people are assigned a different diet. After six months, the blood pressures of each group are compared.

A researcher stood at a school parking lot entrance to see if the color of a car is related to the driver not wearing a seatbelt.

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

Individuals are observed and variables are measured without controlling the individuals or the environment

Individuals are monitored for measures of variables of interest but not influenced in response.

Which scenario is best described as an observational study?

Determine whether the following is an observational study, a survey, or an experiment.

Members of the student council ask every freshman walking into the cafeteria whether they like the snack's in the school's vending machines.

All sample surveys are observational studies