dependent variable

Meaning: The dependent variable (DV) is the outcome a researcher measures. Its value is expected to depend on the independent variable (IV), which the researcher manipulates or, in non-experimental designs, observes as a predictor. In an experiment, a difference in the DV between groups is the effect being tested. A DV needs an operational definition, a concrete way to measure it, such as reaction time in milliseconds or score on a recall test.

On the MCAT: A passage describes a study and asks you to name the IV and DV, predict how the DV changes, or judge whether the measure captures the construct. On a graph, the IV is usually on the x-axis and the DV on the y-axis. Example: participants sleep 4, 6, or 8 hours and then take a recall test; sleep is the IV and recall score is the DV.

Common confusion: Students choose whichever variable sounds more important or appears first. Ask instead which variable the researcher set or used to group participants (the IV) and which was measured as the result (the DV). The same variable can be an IV in one study and a DV in another. In a correlational study there is no manipulation, so causation cannot be concluded even though one variable is treated as the outcome.