What is Minimal Detectable Change (MDC)?

• A. The maximum permissible error in reporting results
• B. The smallest change that exceeds measurement error and reflects real change
• C. A percentage that indicates test fairness
• D. The minimum score needed to pass an assessment

Answer: (B)

Minimal Detectable Change (MDC) refers specifically to the smallest change in a measurement that can be considered statistically significant, as it surpasses the noise of measurement error and indicates a true change has occurred. This concept is crucial in both clinical and research settings where precise tracking of changes is needed to evaluate the effectiveness of interventions or progress over time.

In practice, MDC provides a threshold; if the change in a measured quantity is greater than the MDC value, it is likely that this change reflects a genuine shift in the subject's condition rather than a result of inherent variability in the measurement process. This allows practitioners and researchers to make more informed decisions based on the data collected, ensuring that interventions are appropriately assessed for their impact.

The other options do not accurately capture the definition or purpose of MDC. For instance, some may suggest concepts that relate to passing scores or fairness in testing but do not address the core idea of quantifying measurable change. Understanding MDC is vital for evaluating instruments and ensuring that significant, meaningful changes are recognized in a variety of settings.