Internal Validitiy

An event that affects the participants and changes the dependent variable by occuring between pretest and posttest.

Researchers should do their best to familiarize themselves with what events have or are occuring and use a control group that has not been affected.

Participants naturally change over time (Older, wiser, stronger, etc.)

Researchers should use a control group to eliminate making false connections between effects of the independent variable and natural occurances.

A participant's performance may differ from an initial test because they are now familiar with the testing (not because of treatment or independent variable).

Researchers should use a control group that did not receive any pretesting so that they can compare changes.

Participants performance or testing may result in different results due to changes in instrumentation (misuse, diffent standards of use, etc.).

Researchers should use well-designed instruments and closely follow appropriate steps when implementing.

Preexisting differences betweeen participants in the groups that are not due to the independent variable.

Researchers should use randomization and pretests to make sure there are no differences between the control and experimental group.

When two groups have different maturity levels, the results may not be due to the independent variable.

Researchers should pretest or prescreen groups of participants to ensure both groups do not have varying maturity levels.

Participants in a study (mostly longterm studies) may die or drop out of the study which may alter results in that particular group.

Researchers should obtain background information on participants, use smaller group sizes and provide participants with incentives to complete the study.

Participants attitudes about taking part in a study affect their behavior.

Researchers should try to give similar incentives to the control group as the experimental group to eliminate differences in attitudes.

The expectations of participant's cause results that may be uneffected by the independent variable.

Researchers should make sure both groups receive identical information and to limit that information as much as possible to reduce expectations.

The treatment of one group has an effect on the other group in a similar way.

Researchers should use groups that have less contact with one another if possible and emphasize confidentiality for participants.

Results are affected by differences in the locations of interventions.

Researchers should strive to implement interventions in the same location or locations with as little differences as possible.

Those implementing the program/study influence results (introducing biases or inequality).

Researchers should have a neutral presenter and give him/her specific instructions to follow.

The ability of the researcher to appropriately generalize results of the study to other settings.

To avoid overgeneralizing, researchers need to determine contributing factors and potential, specific differences in the larger group.

The ability of researchers to duplicate the environmental conditions that the experiemental study was done.

Researchers should document original setting in great detail and make sure the study is done in a setting that can be duplicated in the future.

Researchers generalize results of a study to past and future situations.

Researchers should identify specific factors influencing their study and work to incorporate other factors in future studies before overgeneralizing.