Distributions and biological variability
Mean and median describe centers differently when outliers are present.
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Mean and median describe centers differently when outliers are present. Variance and standard deviation describe spread in squared and original units respectively. Biological variability across organisms differs from instrument noise on repeat measurements. Inspect distributions and outliers before choosing a summary; an unusual observation may be a real biological signal or a quality problem.
Worked example
For values [2, 3, 4, 20], the mean is 7.25 and median is 3.5. Report the individual values before claiming that 7.25 represents a typical specimen.