When studies are conducted over a period of time and there is no random assignment to groups, history is not a threat.

Question

Quizplus · Accepted Answer

History is a threat to internal validity in research studies and refers to external events or factors that may influence the outcomes of the study over time. Without random assignment to groups, it may be more difficult to control for these external factors and thus history becomes a greater threat to internal validity.

When Studies Are Conducted Over a Period of Time and There