问题描述
我建立了许多GLM。通常在具有许多模型参数的大型数据集上。这意味着基数R的glm()
函数并不是真正有用的,因为它不能应付大小/复杂性,因此我通常改用revoScaleR::rxGlm()
。
但是,我希望能够对成对的嵌套模型进行ANOVA测试,但我还没有找到对rxGlm()
创建的模型对象执行此操作的方法,因为R的{{1} }函数不适用于它们。 anova()
提供了一种revoScaleR
函数,该函数将as.glm()
对象转换为rxGlm()
对象-有点-但在这里不起作用。
例如:
glm()
工作正常,但是如果我这样做:
library(dplyr)
data(mtcars)
# don't like having named rows
mtcars <- mtcars %>%
mutate(veh_name = rownames(.)) %>%
select(veh_name,everything())
# fit a GLM: mpg ~ everything else
glm_a1 <- glm(mpg ~ cyl + disp + hp + drat + wt + qsec + vs + am + gear + carb,data = mtcars,family = gaussian(link = "identity"),trace = TRUE)
summary(glm_a1)
# fit another GLM where gear is removed
glm_a2 <- glm(mpg ~ cyl + disp + hp + drat + wt + qsec + vs + am + carb,trace = TRUE)
summary(glm_a2)
# F test on difference
anova(glm_a1,glm_a2,test = "F")
我看到错误消息:
library(dplyr)
data(mtcars)
# don't like having named rows
mtcars <- mtcars %>%
mutate(veh_name = rownames(.)) %>%
select(veh_name,everything())
glm_b1 <- rxGlm(mpg ~ cyl + disp + hp + drat + wt + qsec + vs + am + gear + carb,verbose = 1)
summary(glm_b1)
# fit another GLM where gear is removed
glm_b2 <- rxGlm(mpg ~ cyl + disp + hp + drat + wt + qsec + vs + am + carb,verbose = 1)
summary(glm_b2)
# F test on difference
anova(as.glm(glm_b1),as.glm(glm_b2),test = "F")
以前的SO发布中出现了同样的问题:Error converting rxGlm to GLM,但似乎尚未解决。
有人可以帮忙吗?如果Error in qr.lm(object) : lm object does not have a proper 'qr'
component. Rank zero or should not have used lm(..,qr=FALSE)
在这里没有帮助,还有其他方法吗?我可以编写一个自定义函数来做到这一点吗(将我的编码能力扩展到我怀疑的极限!)?
SO还是最好的论坛,还是其他StackExchange论坛之一是寻求指导的更好场所?
谢谢。
解决方法
部分解决方案...
my_anova <- function (model_1,model_2,test_type)
{
# only applies for nested GLMs. How do I test for this?
cat("\n")
if(test_type != "F")
{
cat("Invalid function call")
}
else
{
# display model formulae
cat("Model 1:",format(glm_b1$formula),"\n")
cat("Model 2:",format(glm_b2$formula),"\n")
if(test_type == "F")
{
if (model_1$df[2] < model_2$df[2]) # model 1 is big,model 2 is small
{
dev_s <- model_2$deviance
df_s <- model_2$df[2]
dev_b <- model_1$deviance
df_b <- model_1$df[2]
}
else # model 2 is big,model 1 is small
{
dev_s <- model_1$deviance
df_s <- model_1$df[2]
dev_b <- model_2$deviance
df_b <- model_2$df[2]
}
F <- (dev_s - dev_b) / ((df_s - df_b) * dev_b / df_b)
}
# still need to calculate the F tail probability however
# df of F: numerator: df_s - df_b
# df of F: denominator: df_b
F_test <- pf(F,df_s - df_b,df_b,lower.tail = FALSE)
cat("\n")
cat("F: ",round(F,4),"\n")
cat("Pr(>F):",round(F_test,4))
}
}