881Re: GEOSTATS: Discriminant Analysis
- Jun 21, 1998On Sat, 20 Jun 1998, Palapa wrote:
> If I want to discriminate between two groups ( A and B). Each group hasAs far as I know (AFAIK): Malahanobis distance, used in the
> two variable X and Y ( those variables has different unit ).Between A
> and B has different mean value of X and Y. If I standardize the
> variables, each group will contain zero mean of variable X and Y. So
> the difference matrix A and B is Zero.
> "Do we have to standardize the variables before applying
> discriminant analysis ?"
classification/discrimination algorithm, take care of standardization.
Moreover, why standardize by group ? If you do such a thing, you can only
guess that the two correlation matrix will differ, else you'll get not
any difference between the two groups, but discriminant analysis won't
help in such case.
Recall that the assumption here is that the two covariance/correlation
matrixes (spelled right ?) are equal, else you should use quadratic
discriminant analysis or, to get better results, regularized discriminant
To summarize: don't standardize.
A quite good and free software (MAC and Win95/NT) for Linear Discriminat
Analysis and much more (no cross-validation):
and go to
hope that help
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