effect function in the effects package
Dear Professor Fox,
Now I got it. It all comes from my unfamiliarity with the effect
function. I forgot the c part in the given.values option, plus it
looks like plot(effect()) does not like factor(warm) in the polr
function. So here are the two working lines:
ordwarm2$warm2 <- as.factor(ordwarm2$warm)
myologit <- polr(warm2 ~ yr89 + male + white + age + ed + prst,
data=ordwarm2, method=c("logistic"))
plot(effect("age", myologit, xlevels=list(age=seq(20, 80, 5)),
given.values=(c(male=1, yr89=1))))
Again, thanks a lot for your effects package that makes graphing so much easier.
Jun
On Thu, Oct 20, 2011 at 11:55 AM, John Fox <jfox at mcmaster.ca> wrote:
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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