Taking a Broader Perspective: the Problem of External Validity a Researcher

Multiple Choice

Taking a Broader Perspective: The Problem of External Validity A researcher studying the use of condoms to prevent sexually transmitted disease (STD) combines data from heterosexual and homosexual couples to increase the study's external validity.This pooling of data illustrates

A) aggregation over measures.
B) aggregation over situations.
C) aggregation over subjects.
D) aggregation over trials.