Sampling with and without replacement

In a random sample of size n from a finite population of N values, each population value has the same chance of being in the sample. There are two different ways to select such a sample.

The statistical theory for analysing samples that are taken with replacement (SWR) is also easier than for samples without replacement (SWOR), though this should not affect the sampling scheme that you use!

Practical differences

If the sample size, n, is much smaller than the population size, N, there is little practical difference between SWR and SWOR — there would be little chance of the same individual being picked twice in SWR.

When the population is large (and considerably larger than the sample size), SWR and SWOR are almost identical.

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