Re: [R] Singularity in simple ANCOVA problem

From: RICHARD M. HEIBERGER <rmh_at_temple.edu>
Date: Sun, 20 Jun 2010 20:44:50 -0400

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.

Rich

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