Empirical, Empirical data

The word empirical denotes information gained by means of observation, experience, or experiment.[1] A central concept in science and the scientific method is that all evidence must be empirical, or empirically based, that is, dependent on evidence or consequences that are observable by the senses. It is usually differentiated from the philosophic usage of empiricism by the use of the adjective "empirical" or the adverb "empirically." "Empirical" refers to the use of working hypotheses that are testable using observation or experiment. In this sense of the word, scientific statements are subject to and derived from our experiences or observations. Empirical data are data that are produced by experiment or observation.

The standard positivist view of empirically acquired information has been that observation, experience, and experiment serve as neutral arbiters between competing theories. However, since the 1960s, Thomas Kuhn [2] has promoted the concept that these methods are influenced by prior beliefs and experiences.

Consequently it cannot be expected that two scientists when observing, experiencing, or experimenting on the same event will make the same theory-neutral observations. The role of observation as a theory-neutral arbiter may not be possible. Theory-dependence of observation means that, even if there were agreed methods of inference and interpretation, scientists may still disagree on the nature of empirical data.[3]

In a second sense "empirical" in science may be synonymous with "experimental." In this sense, an empirical result is an experimental observation. In this context, the term semi-empirical is used for qualifying theoretical methods which use in part basic axioms or postulated scientific laws and experimental results. Such methods are opposed to theoretical Ab initio methods which are purely deductive and based on first principles.

In statistics, "empirical" quantities are those computed from observed values, as opposed to those derived from theoretical considerations.
In economics, "empirical" generally refers to statistical or econometric analysis of numeric data. Other forms of observation-based hypothesis testing are not considered to be "empirics."

The use of the adjective empirical, especially in scientific studies using statistics, may also indicate that a particular correlation between two parameters has been found, but that so far, no theory for the mechanism of the connection is known.