[R] accessing confidence interval values from the 'predict' function

[alc]

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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