[R] effect function in the effects package

[John Fox]

Dear Xu Jun,

I'm not sure whether this is the source of the error, but it may help to spell the xlevels argument correctly (it is not "xlevles").

I hope this helps,
 John

------------------------------------------------
John Fox
Sen. William McMaster Prof. of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox/

On Thu, 20 Oct 2011 10:34:30 -0400
 Xu Jun <junxu.r at gmail.com> wrote:
> Dear r-help listers,
> 
> I am using effects to produce an effect plot after the proportional
> odds logistic regression model. There is no problem for me to estimate
> the model, but when it comes to the graphing, I was stuck. see the
> codes below:
> 
> ##############################################################################
>  myologit <- polr(factor(warm) ~ yr89 + male + white + age + ed + prst,
> +               data=ordwarm2, method=c("logistic"))
> 
> require(effects)
> plot(effect("age", myologit, xlevles=list(age=seq(20, 80, 5),
> given.values(male=1, yr89=1))))
> 
> ##############################################################################
> 
> I got the following error message:
> 
> Warning message:
> package 'effects' was built under R version 2.13.2
> Error in plot(effect("age", myologit, xlevles = list(age = seq(20, 80,  :
>   error in evaluating the argument 'x' in selecting a method for
> function 'plot': Error in model.frame.default(formula = factor(warm) ~
> yr89 + male + white +  :
>   variable lengths differ (found for 'yr89')
> 
> 
> the full set of codes:
> 
> > myologit <- polr(factor(warm) ~ yr89 + male + white + age + ed + prst,
> +               data=ordwarm2, method=c("logistic"))
> 
> > summary(myologit)
> 
> Re-fitting to get Hessian
> 
> Call:
> polr(formula = factor(warm) ~ yr89 + male + white + age + ed +
>     prst, data = ordwarm2, method = c("logistic"))
> 
> Coefficients:
>           Value Std. Error t value
> yr89   0.523912   0.079899   6.557
> male  -0.733309   0.078483  -9.344
> white -0.391140   0.118381  -3.304
> age   -0.021666   0.002469  -8.777
> ed     0.067176   0.015975   4.205
> prst   0.006072   0.003293   1.844
> 
> Intercepts:
>     Value    Std. Error t value
> 1|2  -2.4654   0.2389   -10.3188
> 2|3  -0.6309   0.2333    -2.7042
> 3|4   1.2618   0.2340     5.3919
> 
> Residual Deviance: 5689.825
> AIC: 5707.825
> 
> > plot(effect("age", myologit, xlevles=list(age=seq(20, 80, 5), given.values(male=1, yr89=1))))
> Warning message:
> package 'effects' was built under R version 2.13.2
> Error in plot(effect("age", myologit, xlevles = list(age = seq(20, 80,  :
>   error in evaluating the argument 'x' in selecting a method for
> function 'plot': Error in model.frame.default(formula = factor(warm) ~
> yr89 + male + white +  :
>   variable lengths differ (found for 'yr89')
> 
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