14. Sources of data

In the following table, indicate whether the researcher in the scenario is collecting experimental data or observational data.

Scenario

Experimental Data

Observational Data

A sociologist conducts interviews with former protestors and activists in order to study the struggles of the civil rights movement.

An oncologist randomly assigns rats into two groups, giving one group a new drug intended to fight cancer and giving the other group a placebo, in order to study the effects of the new drug.

A medical doctor randomly assigns individuals into two groups, giving one group a new drug to reduce blood pressure and the other group a placebo, in order to study the effects of the new drug.

The issue of reverse causality is more likely to be present in data sets than in data sets.