GIFSQ Tools · Module 16 — Statistics, Experimental Design & Research · Tool 301 of 500
Summarise a set of laboratory results: mean, sample standard deviation, median, quartiles, range and coefficient of variation — the first look at any dataset, per ISO 16269-1.
Try sample values — fills the form with the worked example below.
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Mean
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Standard deviation
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Median
Equation: Mean x̄ = Σx ÷ n. Sample SD s = √(Σ(x − x̄)² ÷ (n − 1)). Median is the middle value. Quartiles use linear interpolation (type 7). CV (%) = s ÷ x̄ × 100. IQR = Q3 − Q1.
Method: Descriptive statistics per ISO 16269-1 (Statistical interpretation of data — Estimation of a mean and related quantities) and ISO 5725-2 (accuracy and precision). Sample SD with n − 1 is the default for laboratory replicates.
Assumptions: the values are replicate measurements of one quantity; the sample SD assumes the values are a sample from a larger set of possible measurements.
Limitations: descriptive statistics do not test anything — a mean and SD cannot say whether two batches differ; use a t-test or ANOVA for that. Quartile definitions differ between software; this tool states its method.
Rounding: mean, SD, median and quartiles to 2 decimal places; CV to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Descriptive statistics per ISO 16269-1 (Statistical interpretation of data — Estimation of a mean and related quantities) and ISO 5725-2 (accuracy and precision). Sample SD with n − 1 is the default for laboratory replicates.
Assumptions: the values are replicate measurements of one quantity; the sample SD assumes the values are a sample from a larger set of possible measurements.
Limitations: descriptive statistics do not test anything — a mean and SD cannot say whether two batches differ; use a t-test or ANOVA for that. Quartile definitions differ between software; this tool states its method.
Rounding: mean, SD, median and quartiles to 2 decimal places; CV to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Values 2, 4, 4, 4, 5, 5, 7, 9: mean 5.00, sample SD 2.14, median 4.50, Q1 4.00, Q3 5.50, CV 42.76%.
Enter values above to see results.
For a quick precision check, compare the CV with your method repeatability limit. Tool 301 of 500 — GIFSQ
