Where does error collide?

In law, error names a mistake made by a court in a legal proceeding, which a higher court may review and, if the mistake changed the outcome, set aside. The old common-law writ of error, described in William Blackstone's 1768 Commentaries on the Laws of England, let a party ask an appellate court to examine the record of a lower court for legal mistakes and reverse the judgment. Modern practice sorts such mistakes by their effect, and Roger Traynor's 1970 The Riddle of Harmless Error examined how courts separate a harmless error from a reversible one. This referent is a defect in a judicial proceeding, judged by whether it affected the verdict, not a deviation of a measurement from a model, a signal that steers a machine, or a lapse in a person's action.[1][2]

Unit

One identified legal mistake in a case record, classified as harmless or reversible

Recovery means

A reversible error is remedied on appeal by reversing or vacating the judgment

Measured by

Identified by appellate review of the trial record and briefs, and graded by legal standards for prejudice

In statistics, the error is the amount by which an observed value departs from the value a model predicts or from the true quantity being estimated, treated as an unavoidable random component rather than a blunder. Adrien-Marie Legendre's 1805 Nouvelles methodes pour la determination des orbites des cometes introduced the method of least squares, which fits a model by making the sum of the squared errors as small as possible. Carl Friedrich Gauss's 1809 Theoria motus corporum coelestium then gave a probabilistic theory of these observational errors and the bell-shaped curve that describes how they scatter. This referent is a numerical residual attached to a measurement or a fitted equation, carrying no notion of blame, unlike a court's reviewable mistake, the signal that drives a controller, or a slip made by a human operator.[3][4]

Unit

A single residual: the observed value minus the fitted or true value, in the data's own units

Recovery means

Not applicable

Measured by

Estimated as residuals from a fitted model and summarised by variance, standard error, or a fitted error distribution

In control engineering, the error is the difference between the value a system is commanded to reach and the value it actually has, and a feedback controller acts on that difference to reduce it. James Clerk Maxwell's 1868 On governors gave the first mathematical analysis of such feedback, studying how a governor counteracts the deviation of a machine's speed from the desired speed. Harry Nyquist's 1932 Regeneration theory then established when a feedback loop that keeps correcting this deviation stays stable rather than breaking into oscillation. This referent is a live signal inside a running machine, continuously computed and driven toward zero, not a residual left after fitting data, a judicial mistake, or a failure of human action.[5][6]

Unit

The instantaneous difference between setpoint and measured output, in the output's units

Recovery means

The loop drives the error back toward zero after each disturbance, at a rate set by the controller

Measured by

Computed continuously as setpoint minus sensor reading, and assessed by its steady-state value and settling behaviour

In human factors and psychology, human error is an action or decision that fails to achieve its intended outcome and was not caused by chance, studied so that systems can be designed to prevent or tolerate it. Paul Fitts and Richard Jones's 1947 analysis of 460 pilot-error incidents in aircraft controls traced many mistakes to confusing instrument and control layouts rather than to careless operators, founding the study of error as a design problem. James Reason's 1990 Human Error then set out the influential division of errors into slips, lapses, and mistakes, tied to different stages of planning and action. This referent is a shortfall in what a person intended to do, analysed to improve people and equipment, not a random residual, a court's reviewable mistake, or a signal steering a machine.[7][8]

Unit

A single erroneous action, decision, or omission, classified by type such as slip, lapse, or mistake

Recovery means

An error may be detected and corrected before harm, and systems add barriers to catch or absorb it

Measured by

Counted from incident reports and observation, and classified by taxonomies of error type and cognitive stage