is that part of statistical practice concerned with the selection of individual observations intended to yield some knowledge about a population of concern, especially for the purposes of statistical inference. Each observation measures one or more properties (weight, location, etc.) of an observable entity enumerated to distinguish objects or individuals. Survey weights often need to be applied to the data to adjust for the sample design. Results from probability theory and statistical theory are employed to guide practice.
The sampling process comprises several stages :
+ Defining the population of concern
+ Specifying a sampling frame, a set of items or events possible to measure
+ Specifying a sampling method for selecting items or events from the frame
+ Determining the sample size
+ Implementing the sampling plan
+ Sampling and data collecting
+ Reviewing the sampling process.