​If research participants are assessed with a particular questionnaire early in a study, but the researchers change the questions for later assessment so participants can't simply repeat answers, what potential threat to internal validity would be likely in the study?​

Correct option is A

The potential threat to internal validity in this situation is Instrumentation. Instrumentation refers to changes in the measurement tools or procedures during the course of a study that can affect the consistency of results. When the researchers modify the questionnaire or measurement tool midway through the study, the difference in assessment methods between the initial and later measurements could lead to inconsistencies in the results, making it difficult to attribute changes in outcomes purely to the intervention or treatment rather than to the changes in the questionnaire itself.

Information Booster:

Instrumentation bias occurs when there are differences in how variables are measured or assessed throughout the study, which can undermine the comparability of results.

Maturation refers to natural changes in participants over time, such as aging or psychological development, that could affect study results, but it does not involve changes in measurement tools.

Attrition refers to participants dropping out of a study, which can threaten internal validity if those who drop out differ in significant ways from those who remain.

History refers to external events that occur during the course of a study and may impact participants, but it does not specifically involve changes to the measurement tool itself.

Additional Information:
​Instrumentation is particularly a concern when the instruments used for measurement are not equivalent at different time points in the study.

Researchers aim to avoid instrumentation threats by using consistent measurement tools throughout the study or by ensuring that any changes in the measurement instruments do not influence the study's outcomes.

The use of pre-post test designs can be especially vulnerable to instrumentation bias if the tests or questionnaires are altered between assessments.