Research Methods in Political Science Practice Exam

Power is the probability of detecting a true effect when one exists. It rises when there is more information and less noise: more observations lessen the standard error, a larger true effect makes the signal easier to pick up, and measuring outcomes more precisely reduces measurement error.

Increasing the sample size adds data, which sharpens the estimate and makes it easier to distinguish a real effect from random variation. Increasing the effect size, when feasible, directly strengthens the signal relative to noise, increasing the likelihood of detecting significance. Using more precise instruments lowers measurement error, cutting down noise in the outcome and improving power.

Increasing measurement error, on the other hand, does the opposite: it inflates noise, obscures true effects, and lowers the probability of detecting an actual effect. That’s why it’s not a recommended way to boost power.