[R] simple question on one-sided p-values for coef() on output of lm()
Prof Brian Ripley
ripley at stats.ox.ac.uk
Wed Feb 21 21:23:55 CET 2007
On Wed, 21 Feb 2007, Ranjan Maitra wrote:
> I was wondering if it is possible to get the p-values for one-sided
> tests on the parameters of a linear regression.
>
> For instance, I use lm() and store the result in an object. lm() gives
> me a matrix, using summary() and coef() on which gives me a matrix
> containing the coefficients, the standard errors, the t-statistics and
> the two-sided p-values by default. Can I get it to provide me with
> one-sided p-values (something like alternative less than or greater
> than)?
Not 'it', but you can easily do the calculation yourself from the output.
E.g.
example(lm)
s <- summary(lm.D90)
pt(coef(s)[, 2], s$df[2], lower=FALSE) # or TRUE
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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