Maturation, regression and experimental mortality are examples of threats to which aspect of a study?

Maturation, regression and experimental mortality are examples of threats to which aspect of a study?

• A. Construct validity
• B. External validity
• C. Internal Validity
• D. Reliability

Answer: (C)

Internal validity focuses on whether observed changes truly come from the experimental manipulation rather than other factors. Maturation is a natural change in participants over time that can alter outcomes independently of the treatment, so improvements or declines might occur simply because people develop or age during the study. Regression to the mean happens when participants are chosen for extreme scores at the start; on subsequent testing their scores tend to move toward the average, which can masquerade as an effect of the intervention. Experimental mortality, or attrition, occurs when participants drop out in a way that biases the remaining sample; if those who leave differ systematically from those who stay, the observed effect may reflect who remained rather than the treatment itself. These issues threaten internal validity because they offer alternate explanations for any observed effects. In contrast, external validity concerns generalizability to other populations or settings, construct validity concerns whether the measures truly reflect the intended constructs, and reliability concerns the consistency of measurements across time or raters. Therefore, these examples are best understood as threats to internal validity.

Internal validity focuses on whether observed changes truly come from the experimental manipulation rather than other factors. Maturation is a natural change in participants over time that can alter outcomes independently of the treatment, so improvements or declines might occur simply because people develop or age during the study. Regression to the mean happens when participants are chosen for extreme scores at the start; on subsequent testing their scores tend to move toward the average, which can masquerade as an effect of the intervention. Experimental mortality, or attrition, occurs when participants drop out in a way that biases the remaining sample; if those who leave differ systematically from those who stay, the observed effect may reflect who remained rather than the treatment itself.

These issues threaten internal validity because they offer alternate explanations for any observed effects. In contrast, external validity concerns generalizability to other populations or settings, construct validity concerns whether the measures truly reflect the intended constructs, and reliability concerns the consistency of measurements across time or raters. Therefore, these examples are best understood as threats to internal validity.