Difference between a measured value of a quantity and its true value
"Systematic bias" redirects here. For the sociological and organizational phenomenon, see Systemic bias.
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Observational error" – news · newspapers · books · scholar · JSTOR(September 2016) (Learn how and when to remove this message)
Observational error (or measurement error) is the difference between a measured value of a quantity and its unknown true value.[1] Such errors are inherent in the measurement process; for example lengths measured with a ruler calibrated in whole centimeters will have a measurement error of several millimeters. The error or uncertainty of a measurement can be estimated, and is specified with the measurement as, for example, 32.3 ± 0.5 cm. (A mistake or blunder in the measurement process will give an incorrect value, rather than one subject to known measurement error.)
Measurement errors can be divided into two components: random and systematic.[2]Random errors are errors in measurement that lead to measurable values being inconsistent when repeated measurements of a constant attribute or quantity are taken. Systematic errors are errors that are not determined by chance but are introduced by repeatable processes inherent to the system.[3] Systematic error may also refer to an error with a non-zero mean, the effect of which is not reduced when observations are averaged.[citation needed] For example, length measurements with a ruler accurately calibrated in whole centimeters will be subject to random error; a ruler incorrectly calibrated will also produce systematic error.
Measurement errors can be summarized in terms of accuracy and precision.
Measurement error should not be confused with measurement uncertainty.
^Dodge, Y. (2003) The Oxford Dictionary of Statistical Terms, OUP. ISBN 978-0-19-920613-1
^John Robert Taylor (1999). An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements. University Science Books. p. 94, §4.1. ISBN 978-0-935702-75-0.
Observationalerror (or measurement error) is the difference between a measured value of a quantity and its unknown true value. Such errors are inherent...
sample from its "true value" (not necessarily observable). The error of an observation is the deviation of the observed value from the true value of a...
the measure varies. The term margin of error is often used in non-survey contexts to indicate observationalerror in reporting measured quantities. Consider...
Accuracy and precision are two measures of observationalerror. Accuracy is how close a given set of measurements (observations or readings) are to their...
In statistical hypothesis testing, a type I error, or a false positive, is the rejection of the null hypothesis when it is actually true. For example...
conclusions from data that are subject to random variation (e.g., observationalerrors, sampling variation). Descriptive statistics are most often concerned...
common error). Independence of observationalerror from potential confounding effects. Exact or approximate normality of observations (or errors). Linearity...
be of various kinds: Sampling from a finite population Measuring observationalerror and refining procedures Studying statistical relations Statistical...
considers only observationalerrors in the dependent variable (but the alternative total least squares regression can account for errors in both variables)...
least squares is a type of errors-in-variables regression, a least squares data modeling technique in which observationalerrors on both dependent and independent...
in a trait are characterized as environmental factors, including observationalerror. In human studies of heritability these are often apportioned into...
such as epidemiology, social sciences, psychology and statistics, an observational study draws inferences from a sample to a population where the independent...
aspects of the set of measurements for an individual or subpopulation. Observationerror Sample point Blalock, Hubert M. Jr. (1972). Social Statistics. New...
continually learn desirable and undesirable behavior through observational learning. Observational learning suggests that an individual's environment, cognition...
testing. The experimental control is a technique for dealing with observationalerror. This technique uses the contrast between multiple samples, or observations...
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes...
complex phenomena; for example, scientists generally assume that the observationalerror in most experiments follows a normal distribution. The Gaussian function...
The standard error (SE) of a statistic (usually an estimate of a parameter) is the standard deviation of its sampling distribution or an estimate of that...
emotionally-biased reasoning to produce justifications or make decisions Observationalerror, also known as Systematic bias – Difference between a measured value...
had isolated observationalerrors resulting from reaction times (the "personal equation") and had developed methods of reducing the errors. The experimental...
is stable, and that the variation between measurements is due to observationalerror. A system of a large number of particles is characterized by the...
the result in the form of upper and lower bounds to account for observationalerror. Ptolemy, quoting Hipparchus, also references Archimedes' solstice...
In statistics, the mean squared error (MSE) or mean squared deviation (MSD) of an estimator (of a procedure for estimating an unobserved quantity) measures...
A false positive is an error in binary classification in which a test result incorrectly indicates the presence of a condition (such as a disease when...
ensemble mean). The 'observationerror covariance matrix' is constructed to represent the magnitude of combined observationalerrors (on the diagonal) and...
morbidity came from observational studies employing regression analysis. In order to reduce spurious correlations when analyzing observational data, researchers...
Global Information