Random assignment of subjects to experimental conditions eliminates the possibility of _________ and __________ as threats to internal validity.
A) maturation; history
B) testing; selection
C) history; statistical regression
D) selection; statistical regression
E) testing; instrumentation

Question

Quizplus · Accepted Answer

Random assignment helps ensure that any differences between groups are due to the experimental treatment rather than pre-existing differences (selection) or changes over time (statistical regression).

Random Assignment of Subjects to Experimental Conditions Eliminates the Possibility