[R] Homework help: Is this how CI using t dist are constructed?
kzembowe at jhuccp.org
Tue Oct 30 21:24:54 CET 2007
I'm trying to replicate some of the examples from my textbook in R (my
text uses Minitab). In this problem, I'm trying to construct a 95%
confidence interval for these distance measurements :
> # Case Study 7.4.1, p. 483
> x <- scan()
1: 62 52 68 23 34 45 27 42 83 56 40
Read 11 items
> mean(x) + qt(c((1-alpha)/2, 1-((1-alpha)/2)), df=length(x)-1) * sd(x)
 36.21420 60.51307
Are confidence intervals with the t distribution constructed using this
type of equation, or am I overlooking a more concise, 'canned' approach
that's already been programmed? Any suggestions on simplifying this?
Thanks for all your advice and help.
 An Introduction to Mathematical Statistics and its Applications,
fourth ed., Larsen and Marx.
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