Dear all,
Does anyone knows how I could extract the p-value in:
> survdiff(Surv(tempo,status) ~ grupo,data=dados1,rho=1)
Call:
survdiff(formula = Surv(tempo, status) ~ grupo, data = dados1, rho = 1)
N Observed Expected (O-E)^2/E (O-E)^2/V
grupo=1 21 5.12 12.00 3.94 14.5
grupo=2 21 14.55 7.68 6.16 14.5
Chisq= 14.5 on 1 degrees of freedom, p= 0.000143
Since with the commands below I cannot.
> fit<-survdiff(Surv(tempo,status) ~ grupo,data=dados1,rho=1)
> attributes(fit)
$names
[1] "n" "obs" "exp" "var"
"chisq" "call"
$class
[1] "survdiff"
I would appreciate any suggestion.
RAL
PS: Please send any to raleandr at carpa.ciagri.usp.br
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I didn't see an obvious way (but there probably is one).
Anyways,
getPval <- function(x)
{
if( is.matrix(x$obs))
etmp <- apply(x$exp, 1, sum)
else
etmp <- x$exp
df<- (sum(1 * (etmp > 0))) - 1
pv <- 1 - pchisq(x$chisq, df)
pv
}
mimics what is done in print.survdiff so it should be correct when
print.survdiff is.
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| Associate Professor fax: (617) 632-2444 |
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| Harvard School of Public Health email: rgentlem at jimmy.dfci.harvard.edu |
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