Validation of a sampling procedure

•We explain why it is important to estimate sampling uncertainty.•We explain detailed calculations for estimating uncertainty using ANOVA.•We present disadvantages and advantages of methods for estimating uncertainty.

Each step of the analytical procedure influences the final results in a significant way. In the majority of cases, the analytical procedure encompasses sampling because the analysis of the entire object (material) is usually impossible, so it is necessary to include the uncertainty related to sampling procedure in the uncertainty-budget calculations.This article describes two basic ways of estimating sampling uncertainty (i.e. experimental and modeling). There is also an example that shows how to estimate uncertainty using analysis of variance (ANOVA).