A simple random sample of n units from a population is a random sample drawn by a procedure that is equally likely to give every collection of n units from the population; that is, the probability that the sample will consist of any given subset of n of the N units in the population is 1/NCn. Simple random sampling is sampling at random without replacement (without replacing the units between draws). A simple random sample of size n from a population of N ≥ n units can be constructed by assigning a random number between zero and one to each unit in the population, then taking those units that were assigned the n largest random numbers to be the sample.