Whether or not a linear model relating the groups makes sense depends on
on the specific groups, so I don't know whether it makes sense in your
context or not. I'll just note that modeling a linear relationship
between groups is a specific hypothesis that assumes that each step up
in the "group" variable yields an identical change in the dependent
variable (since all the groups were themselves spaced by a delta of 1
unit). This is *not* the same as hypothesizing that there is merely a
continuum in the DV such that 1 > 2 > 3 > 4 (or 1 < 2 < 3 < 4).
On Thu, 2012-01-05 at 16:38 +0000, Cagri Yuksel wrote:
> Hello Michael,
> Thank you for your answer. Yes, I realized my mistake about the interpretation of the results right after I sent the message.
> These diagnostic groups are related and this analysis is to test an a priori hypothesis about a possible continuum of GM abnormalities in these groups, that's why I was thinking a linear model.
> Do you think it makes sense ? Do you have other suggestions?
> Thank you again,