During the election time, agencies associated with the publishing media conducts exit polls to forecast the results. They do not base their analysis on the entire population of the country, instead they take a sample of the total population, which is a true representation of the total population. This is one of the best examples of statistical sampling I can think of. Sampling of defects while formulating corrective actions / preventive actions can be a more relevant example of statistical sampling within the project management domain.
In statistics, quality assurance, and survey methodology, sampling is the selection of a subset (a statistical sample) of individuals from within a statistical population to estimate characteristics of the whole population. Statisticians attempt for the samples to represent the population in question. Two advantages of sampling are lower cost and faster data collection than measuring the entire population.