Internal Validity refers to the extent to which a study establishes what?

Internal Validity refers to the extent to which a study establishes what?

• A. The extent to which a study establishes a true cause-and-effect relationship
• B. The extent to which results generalize to other populations
• C. The accuracy of measurement instruments
• D. The reliability of data sources

Answer: (A)

Internal validity is about whether the study design and conduct allow us to claim a cause-and-effect relationship between the intervention and the outcome. When internal validity is strong, we can be confident that observed changes are due to the manipulated variable rather than other factors, such as differences between groups at the start, time-related changes, or measurement artifacts. This depends on good control of bias through appropriate design—random assignment when possible, control groups, blinding, and procedures that minimize threats like history, maturation, testing effects, instrumentation changes, and attrition. By contrast, generalizing results to other populations concerns external validity, while accuracy of measurement instruments and reliability of data sources relate to measurement validity and reliability rather than causal inference. So the statement that internal validity measures the extent to which a study establishes a true cause-and-effect relationship is the best description.

Internal validity is about whether the study design and conduct allow us to claim a cause-and-effect relationship between the intervention and the outcome. When internal validity is strong, we can be confident that observed changes are due to the manipulated variable rather than other factors, such as differences between groups at the start, time-related changes, or measurement artifacts. This depends on good control of bias through appropriate design—random assignment when possible, control groups, blinding, and procedures that minimize threats like history, maturation, testing effects, instrumentation changes, and attrition. By contrast, generalizing results to other populations concerns external validity, while accuracy of measurement instruments and reliability of data sources relate to measurement validity and reliability rather than causal inference. So the statement that internal validity measures the extent to which a study establishes a true cause-and-effect relationship is the best description.