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Re: Oneway Anova from a covariance/cross-product matrix?

From: Jason Stover
Subject: Re: Oneway Anova from a covariance/cross-product matrix?
Date: Tue, 20 Jul 2010 18:37:13 -0400
User-agent: Mutt/1.5.18 (2008-05-17)

On Thu, Jul 08, 2010 at 03:19:14PM +0000, John Darrington wrote:
> However I think this is going to become an unmitigated nuisance.
> We can't always be sure that the dependent variable will be the last
> row/column  and I see that there is code in the fill_covariance function
> in regression.q which rearranges the matrix to satisfy this condition.
> I suggest that instead, we change reg_sweep so that it accepts an integer
> which is the index of the row/column of the dependent variable....

I just made this change.

> On Wed, Jul 07, 2010 at 11:25:32AM -0400, Jason Stover wrote:
>      On Tue, Jul 06, 2010 at 07:09:05PM +0000, John Darrington wrote:
>      > So what exactly do we pass to reg_sweep ?
>      > 
>      > Passing M doesn't seem to help.  If we need to use g or x then that 
>      > requires access to the raw data.  I understood that anova could be 
> calculated 
>      > from M alone.
>      Almost: reg_sweep expects the final column and row to contain the values 
> related to
>      the dependent variable. So it should work with
>          g1         x
>      g1  1.5        3.0
>      x   3.0        16.0
>      Also, that matrix doesn't contain information related to the
>      intercept, or "grand mean," meaning you would need to either include
>      such a column in your covariance matrix, or call
>      post_sweep_computations.
> -- 
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