What is the MDC for the single leg triple hop for distance?

What is the MDC for the single leg triple hop for distance?

• A. 25.50 cm
• B. 28.40 cm
• C. 29.80 cm
• D. 30.96 cm

Answer: (D)

The thing being tested is how much change you must see in the single-leg triple hop for distance to be confident that it reflects a real improvement and not just measurement noise. This is the idea of the minimal detectable change (MDC) at 95% confidence: the smallest change that exceeds the instrument’s and test’s inherent variability. MDC95 is calculated from the standard error of measurement (SEM) and the test’s reliability. SEM comes from how much a score tends to vary when the same person is tested repeatedly, and is computed as SEM = SD × sqrt(1 − ICC), where SD is the score’s standard deviation and ICC is the intraclass correlation for test-retest reliability. The MDC95 then equals SEM × sqrt(2) × 1.96. When you plug in the reliability data for the single-leg triple hop for distance, you get a value around 30.96 cm. So, an improvement greater than about 31 cm from baseline would be interpreted as a real change beyond measurement error, whereas smaller changes could still be within the test’s variability. That’s why the larger value is the appropriate MDC in this context.

The thing being tested is how much change you must see in the single-leg triple hop for distance to be confident that it reflects a real improvement and not just measurement noise. This is the idea of the minimal detectable change (MDC) at 95% confidence: the smallest change that exceeds the instrument’s and test’s inherent variability.

MDC95 is calculated from the standard error of measurement (SEM) and the test’s reliability. SEM comes from how much a score tends to vary when the same person is tested repeatedly, and is computed as SEM = SD × sqrt(1 − ICC), where SD is the score’s standard deviation and ICC is the intraclass correlation for test-retest reliability. The MDC95 then equals SEM × sqrt(2) × 1.96. When you plug in the reliability data for the single-leg triple hop for distance, you get a value around 30.96 cm.

So, an improvement greater than about 31 cm from baseline would be interpreted as a real change beyond measurement error, whereas smaller changes could still be within the test’s variability. That’s why the larger value is the appropriate MDC in this context.