Sampling probability
In statistics, in the theory relating to sampling from finite populations, the sampling probability (also known as inclusion probability) of an element or member of the population, is its probability of becoming part of the sample during the drawing of a single sample. For example, in simple random sampling the probability of a particular unit i {\displaystyle i} to be selected into the sample is p i = ( N − 1 n − 1 ) ( N n ) = n N {\displaystyle p_{i}={\frac {\binom {N-1}{n-1}}{\binom {N}{n}}}={\frac {n}{N}}} where n {\displaystyle n} is the sample size and N {\displaystyle N} is the population size.