Re: [office-formula] CHITEST definition

[Eike Rathke <erack@sun.com>]

Hi Andreas,

On Friday, 2007-03-09 14:36:03 -0700, Andreas J. Guelzow wrote:

> > > Furthermore, Ecma/Excel's definition of degrees of freedom looks weird,
> > > for rows>1 and cols>1 they say it would be (rows-1)*(cols-1). Why?!?
> > 
> > Btw, OOo does the same. Probably because it was documented as such.
> 
> Which test is CHITEST supposed to perform?
> 
> In the cases of a test for independence or a test of homogeneity, these
> degrees of freedom make sense. (But we should have only one regular
> region).

It claims to be an independence test. On the other hand ...

> In the case of a Goodness-of-Fit test one would have observed and
> expected frequencies (corresponding to each other) and the degree of
> freedom should be n-1.

... it gets two arrays passed, one of actual/observed values and one of
expected values. See also the current definition in the latest draft
document uploaded on Friday. If each column of observed values would
represent a different group, matching those of the expected values, what
would n-1 be then? For example:

observed: x,y   expected: X,Y   =CHITEST(A1:B4;D1:E4)

 | A  B  C  D  E
-+--------------
1| x  y     X  Y
2| x  y     X  Y
3| x  y     X  Y
4| x  y     X  Y

How would the (rows-1)*(cols-1) fit in there?


  Eike

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