accessing confidence interval values from the 'predict' function

Dear all,

I'm wondering how can I access the confidence interval values ('upr' and
'lwr' values) produced by the 'predict' function. For example, I fitted
a linear regression line using:

 fit <- lm(y ~ x)

I then wanted to calculate a 95% confidence interval for the line, and
did this using:

 ci <- predict(fit, data.frame(x), interval="confidence")

I see that the 'ci' object has 'upr' and 'lwr' variables stored in it,
but am not sure how to access them properly.

I find I can do it using:

 upper <- as.data.frame(ci)$upr
 lower <- as.data.frame(ci)$lwr

However, I'm wondering is there a more 'proper' way to do it in R? I
find that things like ci$upr don't seem to work, but am not sure what's
the right way?

Kind Regards,

Avril




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