我正在使用效果包构建一些概率图，显示逻辑回归模型的预测概率。但是，我收到一条奇怪的错误消息，不知道问题出在哪里。
当我尝试生成图时，出现以下错误。警告不是问题，而是我不理解错误消息告诉我的内容。
library(effects)
dat$won_ping = as.factor(dat$won_ping)
mod2 = glm(won_ping ~ our_bid +
age_of_oldest_driver2 +
credit_type2 +
coverage_type2 +
home_owner2 +
vehicle_driver_score +
currently_insured2 +
zipcode2,
data=dat, family=binomial(link="logit"))
> plot(effect("our_bid*vehicle_driver_score", mod2), rescale.axis=FALSE, multiline=TRUE)
Warning message:
In analyze.model(term, mod, xlevels, default.levels) :
our_bid:vehicle_driver_score does not appear in the model
Error in plot(effect("our_bid*vehicle_driver_score", mod2), rescale.axis = FALSE, :
error in evaluating the argument 'x' in selecting a method for function 'plot': Error in apply(mod.matrix[, components], 1, prod) :
subscript out of bounds
这是有关我的数据和 glm 命令的信息：
> str(dat)
'data.frame': 85240 obs. of 71 variables:
$ our_bid : num 155 123 183 98 108 159 98 123 98 200 ...
$ won_ping : Factor w/ 2 levels "0","1": 1 1 2 1 1 1 1 1 1 1 ...
$ zipcode2 : Factor w/ 4 levels "1:6999","10000:14849",..: 4 3 2 1 3 2 3 1 2 2 ...
$ age_of_oldest_driver2 : Factor w/ 4 levels "18 to 21","22 to 25",..: NA 3 NA NA NA NA 3 NA 3 NA ...
$ currently_insured2 : Factor w/ 2 levels "0","1": 2 1 2 2 1 1 2 2 1 1 ...
$ credit_type2 : Ord.factor w/ 4 levels "POOR"<"FAIR"<..: 2 3 2 3 2 2 1 3 3 2 ...
$ coverage_type2 : Factor w/ 4 levels "BASIC","MINIMUM",..: 4 3 3 3 3 3 3 3 4 3 ...
$ home_owner2 : Factor w/ 2 levels "0","1": 1 2 2 2 2 2 2 2 2 2 ...
$ vehicle_driver_score : Factor w/ 2 levels "0","1": 1 1 1 1 1 1 1 1 1 1 ...
最后，这里可能是一些有用的信息：
> sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: x86_64-pc-mingw32/x64 (64-bit)
locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252 LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C LC_TIME=English_United States.1252
attached base packages:
[1] grid stats graphics grDevices utils datasets methods base
other attached packages:
[1] effects_2.2-1 colorspace_1.1-1 nnet_7.3-1 MASS_7.3-16 lattice_0.20-0 foreign_0.8-46
loaded via a namespace (and not attached):
[1] tools_2.14.0
帮助！错误信息是什么意思？通常，如果“下标超出范围”，则意味着我正在选择该数据结构范围之外的内容，但这根本不会发生。
编辑：
致@罗兰
正如我上面所说，警告和错误消息是分开且不相关的。假设我取出 zipcode2 并运行 glm：
mod2 = glm(won_ping ~ our_bid +
age_of_oldest_driver2 +
credit_type2 +
coverage_type2 +
home_owner2 +
vehicle_driver_score +
currently_insured2,
data=dat, family=binomial(link="logit"))
> plot(effect("our_bid*home_owner2", mod2), rescale.axis=FALSE, multiline=TRUE)
Warning message:
In analyze.model(term, mod, xlevels, default.levels) :
our_bid:home_owner2 does not appear in the model
这只会产生警告，这很好，因为我得到了想要的结果。因此，“ ： ”没有出现在模型中的事实不是问题，也不会导致错误消息。