When researchers have a plan regarding the comparisons between groups needed to test their research hypotheses, these comparisons are known as ______.

A) planned comparisons
B) unplanned comparisons
C) post hoc comparisons
D) complex comparisons

Planned comparisons are pre-determined comparisons between groups that are necessary to test research hypotheses. Unplanned comparisons occur when additional comparisons are made that were not specifically planned in advance. Post hoc comparisons are comparisons made after the data has been collected and analyzed, often in response to unexpected results. Complex comparisons refer to comparisons that involve several independent variables and their interactions.