Astrophysics (Index)About

systematic error

(errors with non-random characteristics)

A systematic error (plural: systematic errors, often shortened to systematics) of a measurement, such as that by an instrument of a telescope, is a measurement error that is not random, but rather a measurement error inherent in the design of the device. A very simple example is a sensor with a duty cycle, i.e., it is sensing a certain percent of the time but is sensing during the periodic times that data is being unloaded and the resulting measurement of received EMR is skewed. Another simple example is a non-flat sensitivity function of a receiving instrument: the amount received at different wavelengths varies. (These cases are so straight-forward that they hardly deserve the name systematic error, but instruments have far-more-complicated and less-clear examples.) The term may sometimes be used for natural causes, e.g., airmass, and/or may sometimes be known issues with mathematics used. Systematic errors are in contrast to the random errors due to small imperfections in the equipment, or due to over-precise quantification, in effect adding random digits to the end of the quantity. If the systematics are known, the measurements can be culled to avoid them, adjusted to compensate, and/or the sources of error may be noted.


(technology,instruments,telescopes)
Further reading:
https://en.wikipedia.org/wiki/Observational_error#Random_errors_versus_systematic_errors
https://www.physics.umd.edu/courses/Phys276/Hill/Information/Notes/ErrorAnalysis.html
https://www.scribbr.com/methodology/random-vs-systematic-error/
https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch1/errors.html
https://courses.cit.cornell.edu/virtual_lab/LabZero/Experimental_Error.shtml

Referenced by pages:
combined differential photometric precision (CDPP)
HIRAX
Markov chain Monte Carlo (MCMC)
sigma (σ)
speckles
Sys-Rem
volume weighting

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