When sampling without replacement, as in a simple random sample, the SE of sample sums and sample means depends on the fraction of the population that is in the sample: the greater the fraction, the smaller the SE. Sampling with replacement is like sampling from an infinitely large population. The adjustment to the SE for sampling without replacement is called the finite population correction. The SE for sampling without replacement is smaller than the SE for sampling with replacement by the finite population correction factor ((N −n)/(N − 1))^½. Note that for sample size n=1, there is no difference between sampling with and without replacement; the finite population correction is then unity. If the sample size is the entire population of N units, there is no variability in the result of sampling without replacement (every member of the population is in the sample exactly once), and the SE should be zero. This is indeed what the finite population correction gives (the numerator vanishes).