chi-squared tests in python?

Robert Kern robert.kern at
Tue Jan 17 18:55:48 CET 2006

Matthew Vernon wrote:
> Hi,
> I'd like to be able to use the chi-squared test in my code. Currently,
> I can output "look up [this value] in a chi-squared table with [x]
> degrees of freedom", but that's obviously a little sub-optimal. I
> notice that numarray has a chi_square function, but that just gives
> you random numbers from a chi-squared distribution with a set number
> of degrees of freedom - not really what I want.
> Does there exist python code to do this? preferably something vaguely
> standard? 

Yes, in Scipy.

  from scipy.stats import chi2

  # one-sided Chi^2 test
  pval = 1 - chi2.cdf(value, dof)
[This URL will be in a week or so, I hope.]

> Matthew
> ps: given the "batteries included" philosphy, there's a remarkable dearth 
> of stats in python...

I think Chi^2 tests fall distinctly in the "third-party library" category, myself.

Robert Kern
robert.kern at

"In the fields of hell where the grass grows high
 Are the graves of dreams allowed to die."
  -- Richard Harter

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