Which potential threat to internal validity is associated with the tools or instruments used in a study?

Instrumentation refers to the potential threat to internal validity that arises when there are changes in the measurement tools or instruments used to collect data in a study. This can occur if the tools were not used consistently throughout the research, if there are variations in the way data is recorded or interpreted, or if the instruments themselves have been altered or changed in some way during the study period. Such inconsistencies can lead to measurements that do not accurately reflect the true outcomes, thereby affecting the reliability and validity of the study's findings.

For instance, if a researcher uses a questionnaire to assess patient outcomes, any change to the questions, scoring system, or administration process could lead to different results, not because the actual outcomes have changed, but because the measurement tool used to assess those outcomes has been modified. This means that any observed effects may not be attributed accurately to the intervention being studied but instead could be due to the variations in instrumentation.

In contrast, maturation refers to changes in participants that occur over time, such as aging or changes in health status. Threats encompass a range of issues that could potentially affect the validity of the study but are not specific to measurement tools. Reactivity involves changes in participants' behavior due to being observed or measured. These concepts are important in