2018-10-03 18:59:01 +00:00
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# http://stackoverflow.com/questions/20799403/improving-performance-of-cronbach-alpha-code-python-numpy
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# pythran export cronbach(float [][])
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# setup: import numpy as np ; N = 600 ; items = np.random.rand(N,N)
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# run: cronbach(items)
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2018-10-03 12:38:48 +00:00
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2018-04-05 22:07:33 +00:00
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def cronbach(itemscores):
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itemvars = itemscores.var(axis=1, ddof=1)
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tscores = itemscores.sum(axis=0)
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nitems = len(itemscores)
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2018-10-03 18:59:01 +00:00
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return nitems / (nitems - 1) * (1 - itemvars.sum() / tscores.var(ddof=1))
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