Concept

Representative Sample

A sample that accurately reflects the characteristics of the population is called a representative sample.

In a representative sample, if x parts of the population have a certain characteristic, approximately x parts of the sample will share the same characteristic. As an example, consider a sample of cats and dogs selected from all the cats and dogs at a pet shop.

The figure shows cats represent 60 % of the population and 60 % of the sample. Similarly, dogs represent 40 % of the population and 40 % of the sample. In this case, the sample is then representative. Note that in a representative sample, every subgroup of the population is represented.

Extra

Relation with Bias
It is possible that samples reflect biases. In most cases, unbiased samples result in representative samples. On the other hand, biased samples usually result in samples that are not representative of the population.

Exercises
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