[Scipy-tickets] [SciPy] #1388: scipy.stats.linregress is producing negative p-values
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Wed Feb 16 18:19:07 CST 2011
#1388: scipy.stats.linregress is producing negative p-values
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Reporter: mataap | Owner: somebody
Type: defect | Status: new
Priority: normal | Milestone: 0.10.0
Component: Other | Version: 0.8.0
Keywords: |
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Hi,
Shouldn't the p-values, being probabilities, be non-negative? However I
am getting negative p-values for some data sets.
I observed this in scipy v 0.7.1, so I upgraded to 0.10.0 hoping that the
problem would not be in a later version, however, 0.10.0 is still
generating negative p-values.
I notice the negative p-values are associated with negative trend
gradients...
I have attached a python script with a data set in it that illustrates the
problem. Out of 36 data sets I ran, 3 came back with negative p-values.
I am happy to help fix the problem, if it is a problem. If linregress is
designed to return negative p-values as a signal that a trend is negative,
then that should be documented in the manual.
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Ticket URL: <http://projects.scipy.org/scipy/ticket/1388>
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