Message-ID: <55C8AB93.2080705@dewey.myzen.co.uk>
Date: 2015-08-10T13:48:03Z
From: Michael Dewey
Subject: accessing confidence interval values from the 'predict' function
In-Reply-To: <a334c8948115e0d094aa45942d7bccc5@sanger.ac.uk>
Dear Avril
I think you will find that predict.lm returns a matrix not a data frame.
I find str() useful when R does things I did not expect or quite understand.
Michael
On 10/08/2015 09:20, alc wrote:
>
>
> 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
>
>
>
>
--
Michael
http://www.dewey.myzen.co.uk/home.html