Replicate Statistics Calculator: Mean, Sample SD and %RSD

Replicate statistics calculator

Enter two or more measurements in the same units. Separate values with commas, spaces or line breaks. Use a period for decimals. The input limit is 30,000 characters. Scientific notation is accepted. Nonzero magnitudes must round to a finite, nonzero value in the supported numeric range, approximately 5e−324 to 1.7976931348623157e308.

Enter measurements to calculate their summary.

The mean is the sum of the readings divided by n. The sample standard deviation is the square root of the sum of squared deviations from the mean divided by n − 1. Percent relative standard deviation (%RSD) is 100 × sample standard deviation / |mean|, using the absolute mean as defined by NIST Dataplot. This percentage is undefined when the mean is zero and is hard to interpret when the mean is near zero or the scale has an arbitrary zero.

Results are rounded to up to seven significant digits for display and download. A statistic can fall outside the supported numeric range even when all inputs are valid.

Worked example · Repeat injections

Three fictional injections of one prepared sample gave 9.8, 10.1 and 10.1 mg. The mean is 30.0 ÷ 3 = 10.0 mg. The squared deviations sum to 0.06 mg². Dividing by 2 and taking the square root gives a sample SD of about 0.1732 mg and an RSD of about 1.73%.

Enter the example with decimal points as 9.8, 10.1, 10.1 and use mg in the separate unit field. One injection is one observation. Compare with independent preparations.