Statistics is the discipline that concerns the gathering, organization, analysis, interpretation, and presentation of knowledge. In applying statistics to a scientific, industrial, or social problem, it's conventional, to start with a statistical population or a statistical model to be studied. Populations are often diverse groups of individuals or objects like "all people living during a country" or "every atom composing a crystal". Statistics deals with every aspect of knowledge, including the planning of knowledge collection in terms of the design of surveys and experiments. See the glossary of probability and statistics.

When census data can't be collected, statisticians collect data by developing specific experiment designs and survey samples. Representative sampling assures that inferences and conclusions can reasonably extend from the sample to the population as an entire.