aov bug? (PR#1930)
ripley@stats.ox.ac.uk
ripley@stats.ox.ac.uk
Fri, 23 Aug 2002 06:54:41 +0100 (BST)
Maybe, but this is exactly what S does, and `weights' is not a documented
argument to aov().
I will alter print.aov to use the weighted form.
On Thu, 22 Aug 2002 iwhite@staffmail.ed.ac.uk wrote:
>
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> Version 1.4.0 (2001-12-19)
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> > invisible(options(echo = TRUE))
> > R.version
> _
> platform i686-pc-linux-gnu
> arch i686
> os linux-gnu
> system i686, linux-gnu
> status
> major 1
> minor 4.0
> year 2001
> month 12
> day 19
> language R
> > r <- c(10,23,23,26,17,5,53,55,32,46,10,8,10,8,23,0,3,22,15,32,3)
> > n <- c(39,62,81,51,39,6,74,72,51,79,13,16,30,28,45,4,12,41,30,51,7)
> > trt <- factor(rep(1:4,c(5,6,5,5)))
> > Y <- r/n
> > z <- aov(Y ~ trt,weights=n)
> > summary(z)
> Df Sum Sq Mean Sq F value Pr(>F)
> trt 3 16.0626 5.3542 12.330 0.0001577 ***
> Residuals 17 7.3820 0.4342
> ---
> Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1
> > z
> Call:
> aov(formula = Y ~ trt, weights = n)
>
> Terms:
> trt Residuals
> Sum of Squares 16.062629 0.395016
> Deg. of Freedom 3 17
>
> Residual standard error: 0.1524343
> Estimated effects may be unbalanced
> >
> > # BUG? summary(z) correctly reports the weighted residual sum of squares,
> > # but the output from z gives an unweighted residual sum of squares.
> > # At the least the discrepancy between the two forms of output is
> > # confusing.
> > proc.time()
> [1] 1.60 0.08 1.65 0.00 0.00
> >
>
> ======================================
> I.White
> ICAPB, University of Edinburgh
> Ashworth Laboratories, West Mains Road
> Edinburgh EH9 3JT
> Fax: 0131 667 3210 Tel: 0131 650 5490
> E-mail: iwhite@staffmail.ed.ac.uk
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--
Brian D. Ripley, ripley@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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