During the course of her experiment, Yolanda learned that 7 of the 12 clients in her new 4-hour session had quit and walked out of the session before it was completed. What threat to internal validity does her experiment have?
A) experimental mortality
B) history effect
C) selection bias
D) maturation

Question

Quizplus · Accepted Answer

Experimental mortality refers to the loss of participants from a study before it is completed, which is exactly what happened in Yolanda's experiment when 7 out of the 12 clients quit before the session was completed. This can threaten the internal validity because it might mean the results are not representative of the entire group that was initially intended to be studied.

During the Course of Her Experiment, Yolanda Learned That 7