On Wed, 15 Dec 1999 [EMAIL PROTECTED] wrote:
> Will someone please enlighten me as to the general differences between
> GLM and ANOVA. In my short journey through graduate statistics, I
> somehow assumed they were the same.
Parallelling your short journey, here is a short distinction in one
sentence. (Some might want to quibble about details.)
GLM, as its name (General Linear Models) implies, is more
general than ANOVA (ANalysis Of VAriance), which is that subset of GLM
whose predictors (aka independent variables, aka factors) are categorical
(aka of nominal scale).
To elaborate:
In some contexts (e.g., for some packaged statistical programs)
ANOVA -- which in these contexts usually means "factorial ANOVA" -- is
further restricted to balanced designs, sometimes to balanced complete
designs.
In other contexts (as in "the ANOVA summary table"), ANOVA is
much more general -- as general as GLM, actually. The phrase often
refers to the partitioning of variance (in a response variable, aka a
dependent variable or DV) into random ("error") and systematic
components. (There may be more than one of each kind, reflecting the
structure of the design that generated the data.) In this sense, one
encounters analysis of variance as part of the output of a multiple
linear regression (MLR) analysis. (MLR is that subset of GLM whose
predictors are [treated as] "quantitative", meaning quasi-continuous,
aka of interval scale.)
-- DFB.
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Donald F. Burrill [EMAIL PROTECTED]
348 Hyde Hall, Plymouth State College, [EMAIL PROTECTED]
MSC #29, Plymouth, NH 03264 603-535-2597
184 Nashua Road, Bedford, NH 03110 603-471-7128
