此R错误消息是什么意思

Question

I am trying to predict a value for certain variable on my model, together with 95% confidence interval and I keep getting the same error that one of my variables is not found.

Here is the code bit and error message I am getting:

pred.frame <- data.frame(lpsa=seq(min(prostate$lpsa), max(prostate$lpsa),
+ length=100))

pp <- predict(pros8.lm, int="p", newdata=pred.frame)
Error in eval(expr, envir, enclos) : object 'lcavol' not found

I've created a data frame with all of my variable included, together with specific values I want to test, but from some reason it does not identify one of them.

Here is the created data frame:

newpatient <- data.frame(lcavol = 1.44692, lweight = 3.62301, age = 65.0,
lbph = 0.3001, svi = 0.0000, lcp = -0.79851,
gleason = 7.0, pgg45 = 15.0)

Can someone identify/point out why this does not work?

Answer 1

In predict you're specifying the newdata to use is pred.frame . But in pred.frame , there is no column lcavol (that your model pros8.lm needs to make a prediction.

You might want this:

    predict(pros8.lm, int="p", newdata=newpatient)