On 27 Dec 2022, at 18:55 , Greg Snow <538280 at gmail.com> wrote:
Why compute the differences manually when `aov` can do paired
comparisons on this data as is:
summary(aov(extra ~ factor(group) + Error(ID), data=sleep ))
gives the same F and P values
On Tue, Dec 27, 2022 at 3:32 AM Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
Good idea.
On Mon, Dec 26, 2022 at 12:59 PM peter dalgaard <pdalgd at gmail.com> wrote:
My usual advice on getting nonstandard F tests out of anova() is to fit the models explicitly and compare.
So how about this?
fit1 <- lm(diff(extra,10) ~ 1, sleep)
fit0 <- update(fit1, ~ -1)
anova(fit0, fit1)
-pd
On 26 Dec 2022, at 13:49 , Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
Suppose we want to perform a paired test using the sleep data frame
with anova in R. Then this works and gives the same p value as
t.test(extra ~ group, sleep, paired = TRUE, var.equal = TRUE)
ones <- rep(1, 10)
anova(lm(diff(extra, 10) ~ ones + 0, sleep)
This gives output but does not give an F test at all.
ones <- rep(1, 10)
anova(lm(diff(extra, 10) ~ 1, sleep)
Maybe there should be some way to force an F test to be produced for
the intercept in anova for consistency with t.test so that the second
code can be used.
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