Re: [R] Singularity in simple ANCOVA problem

From: Robert A LaBudde <>
Date: Sun, 20 Jun 2010 20:48:07 -0400

At 08:44 PM 6/20/2010, RICHARD M. HEIBERGER wrote:
>You have only one Age value in each Lot. Hence the Age is aliased
>with one of the
>5 degrees of freedom between lots. You can see it in the picture
>xyplot(Conc ~ Age|Lot, data=blots, pch=16)
>There is no opportunity for a slope within each of the groups.



Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail:
Least Cost Formulations, Ltd.            URL:
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"Vere scire est per causas scire" mailing list PLEASE do read the posting guide and provide commented, minimal, self-contained, reproducible code. Received on Mon 21 Jun 2010 - 00:51:16 GMT

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