Have you considered "predict.lm", at least in R 1.9.1? (If I
understand your question, it is answered in the "examples" to
"predict.lm".)
hope this helps.
p.s. I believe this is described in Venables and Ripley, Modern Applied
Statistics with S, but I don't have this book at my fingertips. Also,
have you read the posting" guide!
http://www.R-project.org/posting-guide.html"? Its suggestions might
help you get quicker answers for yourself without waiting for this list
to reply and might improve the quality of the replies to questions you
submit.
?????????????? ???????????? wrote:
>I have one problem with finding the appropriate functions in R that would
perform this operation: We have X, the independent variable, and Y, the response
variable, so that a regression line of these variables can be calculated. Using
the Student t distribution, we need to find the 95% prediction interval of the
mean of Y for the certain value of X. For example, R has the built-in data (
data(cars) ) for cars' speed as the independent variable and cars'
stopping distance as the response variable. Find 95% prediction interval of mean
stopping distance for cars speeding at 30.
>
>I have another question: is there a certain function in R that can calculate
the probability p using the Student t distribution given the certain value, the
sample mean, and the sample standard deviation, and df (i.e., the one that
functions like pnorm(), but deals with Student t distribution.)
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>
>
--
Spencer Graves, PhD, Senior Development Engineer
O: (408)938-4420; mobile: (408)655-4567