Reliability (statistics)

In statistics and psychometrics, reliability is the overall consistency of a measure.^[1] A measure is said to have a high reliability if it produces similar results under consistent conditions:

"It is the characteristic of a set of test scores that relates to the amount of random error from the measurement process that might be embedded in the scores. Scores that are highly reliable are precise, reproducible, and consistent from one testing occasion to another. That is, if the testing process were repeated with a group of test takers, essentially the same results would be obtained. Various kinds of reliability coefficients, with values ranging between 0.00 (much error) and 1.00 (no error), are usually used to indicate the amount of error in the scores."^[2]

For example, measurements of people's height and weight are often extremely reliable.^[3]^[4]

^ William M.K. Trochim, Reliability
^ National Council on Measurement in Education http://www.ncme.org/ncme/NCME/Resource_Center/Glossary/NCME/Resource_Center/Glossary1.aspx?hkey=4bb87415-44dc-4088-9ed9-e8515326a061#anchorR
^ al.], Neil R. Carlson ... [et (2009). Psychology : the science of behaviour (4th Canadian ed.). Toronto: Pearson. ISBN 978-0-205-64524-4.
^ The Marketing Accountability Standards Board (MASB) endorses this definition as part of its ongoing Common Language: Marketing Activities and Metrics Project Archived 12 February 2013 at the Wayback Machine.

[1] William M.K. Trochim, Reliability

[2] National Council on Measurement in Education http://www.ncme.org/ncme/NCME/Resource_Center/Glossary/NCME/Resource_Center/Glossary1.aspx?hkey=4bb87415-44dc-4088-9ed9-e8515326a061#anchorR

[3] .], Neil R. Carlson ... [et (2009). Psychology : the science of behaviour (4th Canadian ed.). Toronto: Pearson. ISBN 978-0-205-64524-4.

[themasb.org-4] The Marketing Accountability Standards Board (MASB) endorses this definition as part of its ongoing Common Language: Marketing Activities and Metrics Project Archived 12 February 2013 at the Wayback Machine.

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