Which statistical term is the best index of precision when comparing two CBC parameters?

The coefficient of variation is the best index of precision when comparing two complete blood count (CBC) parameters because it expresses the extent of variability in relation to the mean of the data set. This statistical measure is particularly useful for comparing the degree of variation between different parameters, regardless of the units of measurement. Since it is calculated as the ratio of the standard deviation to the mean, it provides a normalized measure of dispersion, allowing for an effective comparison of precision across various CBC values that might be on different scales.

Using the coefficient of variation allows clinicians and laboratory professionals to assess the reliability and consistency of test results. For example, if two CBC parameters show the same standard deviation but have different means, their coefficients of variation will indicate which parameter has more relative variability. This helps in understanding how stable and precise the measurements are in clinical practice, guiding appropriate clinical decisions.