Strengths and Weaknesses

Simplicity in the research design

Cost-effective & timely - ideal if results aid in time-sensitive issues

Participant retention - participants that receive some benefits from the study are more likely to stay in the experiment

Pre-test scores - having a pre-test score can verify that randomization did produce similar groups

Generalizability - Steps can be taken to make experiments more generalizable to the broader population

Cause & Effect - Allows us to determine causal relationships

Multiple groups - can study multiple control and experimental groups simultaneously

Control & Replication - researchers have great control over which controls participants are subject to and typically are easier to replicate than other types of studies

Internal validity - experimental designs have the ability to link cause and effect by controlling variables leading to high internal validity

Unequal randomization - since random assignment is based on probability, there is the possibility of imbalanced populations formed in the control or experimental groups

Issues with external validity

Threats to internal validity due to confounding (third) variables

Testing effect - in the pre-test-post-test design, the pre-test may sensitize the control group to the treatment, impacting the post-test scores. This may make the more treatment effective than it would have been without the test

Risk of participant attrition - participants may drop out if the study is too lengthy or if participants feel they are not receiving any benefits from the study.