Coefficient Alpha or Cronbach's Alpha

Coefficient Alpha (also called "alpha") is a statistical value indicating the degree of internal consistency of items in a multiple-item scale like survey items or Likert-type scales.

Internal consistency is one measure of reliability for scores from scales, measures, and survey items.

The alpha statistic was developed by Lee Cronbach in 1951 thus it is also called Cronbach's alpha. In research reports, you may just see the Greek lower case letter alpha, α.

The procedure to calculate alpha can be found in SPSS under Analyze > Scale > Reliabilty.

For research purposes, scales with alpha levels equal to or above alpha = .70 are acceptable. The best scales have values of alpha = .9 or higher.

The alpha method works best to evaluate unidimensional measures. If there are two or more dimensions in a set of items, the alpha value will be lower so, when alpha values are low, consider which item or items do not support the primary dimension.

Cite this Post

Sutton, G.W. (2021, April 26). Coefficient Alpha or Cronbach’s Alpha. Retrieved from https://statistics.suttong.com/2021/04/coefficient-alpha-or-cronbachs-alpha.html

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