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Wald–Wolfowitz test

a nonparametric test of the null hypothesis that two samples have been taken from identical populations, based on whether the number of runs or sequences in an ordering is random. For instance, consider the following ordering of males (M) and females (F) from 1 to 27 according to their performance on a task:
   MMMFFFMMMMFFMMMFFFFFFFMMFMM
.
In this data set, there are nine runs. If the two samples are from the same population, then the males and females will be well mixed and the number of runs thus will be large (e.g., close to 25); if the number of runs is small, as in this example, the ordering cannot be caused by chance fluctuation and the null hypothesis thus is rejected. Also called runs test. [Abraham Wald (1902–1950), Hungarian-born mathematician; Jacob Wolfowitz (1910–1981), U.S. psychologist]

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Psychology term of the day

June 18th 2024

two-parameter model

two-parameter model

in item response theory, a model that specifies two parameters affecting an individual’s response to a particular test item: (a) the difficulty level of the item and (b) the item discriminability. See also Rasch model; three-parameter model.