## [ai-geostats] discriminant analysis?

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• hello mail list I have a categorical variable that describe rock type and I m interesting in quantify the relation and discriminant capacity of continuous
Message 1 of 4 , Mar 16, 2005
hello mail list

I have a categorical variable that describe rock type and I'm
interesting in quantify the relation and discriminant capacity of
continuous variables (grade elements) over each category.

The problem is that I have no normality over the domain and the classes,
the variance and covariances are not the same, and the categories are
not independent, that limit for example the Discriminant analysis, some
alternative (example logistic regression )?

a) what to use as statistical method?
b) is possible to use discriminant analysis?

Regards
• Re : Use of discriminant analysis: You might try quadratic disciminant analysis, wherein differences among variances and covariances are taken into account.
Message 2 of 4 , Mar 16, 2005
Re : Use of discriminant analysis: You might try quadratic
disciminant analysis, wherein differences among variances and
covariances are taken into account. You don't describe how far the
class distributions are from being normally distributed - but in some
cases data transformations (e.g. applying the log transformation to
skewed data) will make the data normally distributed or almost so.
In any case, it's a good idea to get a measure of performance -
splitting data with class identifications into training (for
computing discriminants) and test (for computing accuracy of
discriminat anaoysis) subsets if you have sufficient data, or
jacknifing in the case of fewer data.

>hello mail list
>
>I have a categorical variable that describe rock type and I'm
>interesting in quantify the relation and discriminant capacity of
>continuous variables (grade elements) over each category.
>
>The problem is that I have no normality over the domain and the classes,
>the variance and covariances are not the same, and the categories are
>not independent, that limit for example the Discriminant analysis, some
>alternative (example logistic regression )?
>
>a) what to use as statistical method?
>b) is possible to use discriminant analysis?
>
>Regards
>
>
>
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--
***************************************
Chris Hlavka
NASA/Ames Research Center 242-4
Moffett Field, CA 94035-1000
(650)604-3328 FAX 604-4680
Christine.A.Hlavka@...
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• Hi, Martinez, It seems to me that you are analysing coded categorical variables (eg. soft = 1, coarse = 2, hard = 3 etc.). I also assume that your coding is
Message 3 of 4 , Mar 16, 2005
Hi, Martinez,

It seems to me that you are analysing coded categorical variables (eg. soft
= 1, coarse = 2, hard = 3 etc.). I also assume that your coding is not
examination.

To be able to answer your question I would like to know the nature of your
response variable (usually called regressand or predictand etc.). Especially
I would like to know if it is a continuous variable or a categorical
variable. If it is a categorical variable, how many levels do you have for
it? Bionomial or multinomial? Ordered or nomial?

If you have bionomial dependent variable you can use logistic regression or
binary probit. Even though their distribution assumptions are different, the
final conclusion will be the same. If you have ordered variable, you can use
ologit (ordered logit) or oprobit (ordered probit). If you have multi-level
nominal variable, you can use multinomial regression analysis.

You can use discriminat analysis, but I would rather go for logist or probit

If you need more help, pleas contact me.

I hope this helps a little bit.

Cheers
Mahdi

> hello mail list
>
> I have a categorical variable that describe rock type and I'm
> interesting in quantify the relation and discriminant capacity of
> continuous variables (grade elements) over each category.
>
> The problem is that I have no normality over the domain and the classes,
> the variance and covariances are not the same, and the categories are
> not independent, that limit for example the Discriminant analysis, some
> alternative (example logistic regression )?
>
> a) what to use as statistical method?
> b) is possible to use discriminant analysis?
>
> Regards
>
>
>
>

--
-----------------------------------
Mahdi Osman (PhD)
E-mail: m_osm@...
-----------------------------------

DSL Komplett von GMX +++ Supergünstig und stressfrei einsteigen!
AKTION "Kein Einrichtungspreis" nutzen: http://www.gmx.net/de/go/dsl
• Hi all: Sorry to disturb with a different question, I was wondering if anyone could point out some good references on multilevel modeling within a spatial
Message 4 of 4 , Mar 18, 2005
Hi all:

Sorry to disturb with a different question, I was wondering if anyone could
point out some good references on multilevel modeling within a spatial
framework, besides the work of the folks creators of Mlwin.

Gaston Pezzuchi

> hello mail list
>
> I have a categorical variable that describe rock type and I'm
> interesting in quantify the relation and discriminant capacity of
> continuous variables (grade elements) over each category.
>
> The problem is that I have no normality over the domain and the classes,
> the variance and covariances are not the same, and the categories are
> not independent, that limit for example the Discriminant analysis, some
> alternative (example logistic regression )?
>
> a) what to use as statistical method?
> b) is possible to use discriminant analysis?
>
> Regards