R help - Aug 2011 - Ordered probit model -marginal effects and relative importance of each predictor-

Hi, I have a problem with the ordered probit model -polr function
(library MASS). My independent variables are countinuos.
I am not able to understand two main points:

a) how to calculate marginal effects
b) how to calculate the relative importance of each independent variables

If required i will attach my model output.

Thanks

Franco

On Aug 27, 2011, at 3:15 PM, franco salerno wrote:
> Hi, I have a problem with the ordered probit model -polr function
> (library MASS). My independent variables are countinuos.
> I am not able to understand two main points:
>
> a) how to calculate marginal effects
> b) how to calculate the relative importance of each independent  
> variables
>
> If required i will attach my model output.
It is a great puzzle to me that people think that the output of a  
statistical program can be interpreted without a clear and complete  
description of the input.

-- 
David Winsemius, MD
West Hartford, CT

On Aug 27, 2011 franco salerno wrote:
> ...problem with ordered probit model -polr function (library MASS).
> a) how to calculate marginal effects
> b) how to calculate the relative importance of each independent variables
Hi Franco,

Have a look at John Fox's effects package (for a), and the Anova() function
in his car package (for b).

Regards, Mark.

-----
Mark Difford (Ph.D.)
Research Associate
Botany Department
Nelson Mandela Metropolitan University
Port Elizabeth, South Africa
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late to the game but maybe this will help:

https://docs.google.com/viewer?a=v&q=cache:8PhCkZxP9zQJ:www.quantoid.net/Effects_package_4up.pdf+plot+effects+of+variables+in+R+nonlinear+arrows&hl=en&gl=us&pid=bl&srcid=ADGEEShUKOEcifzuWGxWvakh0yD4KtnLgBhLFvX5cCAkwewyQ75uznTw1OYybx6vrGuJflgMw6QYKGwuXQViNGZCh_lt8H4DAqKNPxI8y2hYTQJTyaMD4tZ0DKrYMNGtIY3B34qp-LBX&sig=AHIEtbTdt10fNCOPXtg5nPSs85NqPFlAvA

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