random sampling

Sampling 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. Results from probability theory and statistical theory are employed to guide practice.
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Noun
1. the selection of a random sample; each element of the population has an equal chance of been selected
(hypernym) sampling
(hyponym) lucky dip

a sampling method where everyone in the chosen universe has an equal chance of being included. This method will not guarantee that the sample will be free from bias - only that the method of selection is free from bias.