Professor Dalgaard,
Thank you for your reply. My question: shouldn't every statistical function in
R, every statistical procedure, have some reference in the respective Help file?
Basic functions like sqrt, log, sort, sample, these are part of the base system
in R, they generally have a clear purpose, a clear calculation to perform, and
they are supposed to work well, no matter the exact details of their
mathematical methods.
But higher level statistical functions, like prop.trend.test, or glm, they each
perform some calculations according to a given method, but the method could
possibly be somewhat different from the one implemented, with possible
variations in the results.
Shouldn't the methods of statistical functions be always documented in the Help
files, with references? Why there is just no information about the method of
prop.trend.test?
Thank you once again for your attention.
Paulo Barata
Rio de Janeiro - Brazil
-------------------------------------------------------
On 12-Nov-25 9:49, Peter Dalgaard wrote:
There's a worked example of the procedure in Altman: Practical Statistics for
Medical Research, also featured in help(ISwR::caesarean).
(I have forgotten the origin of example(prop.trend.test), though. If I ever
knew it. Apparently it is the same as in help(prop.test): Fleiss(1981), p.139,
but I don't have that edition to hand and I don't see it in Fleiss(1973).)
-pd
On 12 Nov 2025, at 11.55, Michael Dewey <[email protected]> wrote:
Dear Paulo
You did realise that if you type prop.trend.test you get
function (x, n, score = seq_along(x))
{
method <- "Chi-squared Test for Trend in Proportions"
dname <- paste(deparse1(substitute(x)), "out of", deparse1(substitute(n)),
",\n using scores:", paste(score, collapse = " "))
x <- as.vector(x)
n <- as.vector(n)
p <- sum(x)/sum(n)
w <- n/p/(1 - p)
a <- anova(lm(freq ~ score, data = list(freq = x/n, score =
as.vector(score)),
weights = w))
chisq <- c(`X-squared` = a["score", "Sum Sq"])
structure(list(statistic = chisq, parameter = c(df = 1),
p.value = pchisq(as.numeric(chisq), 1, lower.tail = FALSE),
method = method, data.name = dname), class = "htest")
}
<bytecode: 0x0000021d81d4c850>
<environment: namespace:stats>
Does that help?
Michael
On 11/11/2025 18:27, Paulo Barata wrote:
To the R-Help list,
About the prop.trend.test function, in the package stats.
What calculations exactly does that function perform? What test is actually
carried out? May I have some reference for the calculations performed by that
function?
I would like to suggest that some references (one or more) be included in the
Help file for the function.
Thank you very much.
Paulo Barata
Rio de Janeiro - Brazil
______________________________________________
[email protected] mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting- guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Michael Dewey
______________________________________________
[email protected] mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
[email protected] mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
