All Glossary

Representative Sample

In a testing process, it is important that the sample being tested is representative of the entire lot being evaluated. In production, this could be thousands of bags, boxes, tons, etc. Representative samples are essential, for example, when evaluating a clay deposit for mining, when testing a stockpile for use or when testing batches of powder, slurry, pelletized or pugged material for quality assurance.

The term "representative" refers specifically to the property being evaluated. For example, powders being evaluated for particle size distribution need to be sampled in such a way that the distribution of particle sizes in the sample is representative of the entire batch being tested. Small samples may be extracted from multiple points during a production run, mixed and thereby judged to be representative of the entire run. Such sampling does not speak to the consistency of a property within a run.

Related Information

A three pan sample-splitter

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Powdered or small-lumped clay is poured into the top and split, half going into each pan below. The cycle is repeated until the desired sample size is achieved. The objective is a representative sample. This is especially important in particle size distribution testing but also for any other kind of testing to evaluate the suitability or consistency of a batch or sample.

Preparing a representative sample of dry material

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Repeat a cycle of layering to create a pile of material, quartering it, removing opposite quarters and remixing. Do this until the amount needed for testing is achieved.

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