A sample is composed of products selected at random from a given lot for inspection.
Why inspect only a sample?
For large orders, inspecting the whole quantity would take many days of work.
And inspecting just a sample should give relatively similar results as inspecting the whole lot if a proper product inspection procedure is followed (explore Sofeast’s product inspection solutions here).
The selection chosen should be as similar to the whole lot as possible in its composition. For example, if half the lot is black and the other half is white, the same proportions of each color should be present.
ISO 2859 definition for “sample”
“The items selected for the sample shall be drawn from the lot by simple random sampling. However, when the lot consists of sub-lots or strata, identified by some rational criterion, stratified sampling shall be used in such a way that the size of the subsample from each sublot or stratum is proportional to the size of that sublot or stratum.”