Three data sampling methods: Random sampling - selecting a person to interview or site to measure, at random. Random sampling is unbiased as particular people or places are not specifically selected.

Three data sampling methods: Random sampling - selecting a person to interview or site to measure, at random. Random sampling is unbiased as particular people or places are not specifically selected.

Therefore, the size of the sample is a random variable. Two estimators of a population total under this sampling procedure are compared with the usual estimator under simple random sampling.