Displaying 6 results from an estimated 6 matches for "tsampl".
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2003 Sep 03
0
Updated power.t.test
...d's must be positive")
}
else {
if (sum(sapply(list(n, delta, sd, power, sig.level), is.null)) != 1)
stop("exactly one of n, delta, sd, power, and sig.level must be NULL")
}
alternative <- match.arg(alternative)
df.method <- match.arg(df.method)
tsample <- switch(type, one.sample = 1, two.sample = 2, paired = 1)
tside <- switch(alternative, one.sided = 1, two.sided = 2)
if (tside == 2 && !is.null(delta))
delta <- abs(delta)
p.body <- quote({
nu <- switch(tsample, n-1, switch(df.method, welch=(sd^2/n + (sd*sd....
2003 May 30
1
power.t.test needs to check delta==NULL before abs(delta) (PR#3139)
...wer.t.test to make
sure that it doesn't try to evaluate abs(NULL), which results in an
error.
--- rossini.power.t.test.R 2003-05-30 07:24:49.000000000 -0700
+++ rossini.power.t.test.R.~1~ 2003-05-30 08:47:09.000000000 -0700
@@ -10,7 +10,7 @@
alternative <- match.arg(alternative)
tsample <- switch(type, one.sample = 1, two.sample = 2, paired = 1)
tside <- switch(alternative, one.sided = 1, two.sided = 2)
- if (tside == 2 && !is.null(delta))
+ if (tside == 2)
delta <- abs(delta)
p.body <- quote({
nu <- (n - 1) * tsample
--please do not edi...
2004 May 12
1
Formula of power.t.test
Dear Sir or Madam,
What is the formula for power.t.test(delta=delta, sd=segma, sig.level=0.05,
power=0.8, type="one.sample", alternative="one.sided")$n?
Thank you very much for the help!
Best,
Xiaorong
2001 Sep 30
1
(No Subject)
Dear all
I am very beginner user of R I want to calculate the power of t-test using power.t.test function. It is stated in the manual that the argument (n) is the number of observations per group. Infact I have a differens number of observations in each group(ie n1<>n2) and another thing is SD the pooled standard deviation of the observations in the two data sets under investigation.
Hope
2003 May 30
0
power.t.test needs to check delta==NULL before abs(delta) (PR#3140)
...error.
That's a backwards patch, I presume, or you revert the fix.
> --- rossini.power.t.test.R 2003-05-30 07:24:49.000000000 -0700
> +++ rossini.power.t.test.R.~1~ 2003-05-30 08:47:09.000000000 -0700
> @@ -10,7 +10,7 @@
> alternative <- match.arg(alternative)
> tsample <- switch(type, one.sample = 1, two.sample = 2, paired = 1)
> tside <- switch(alternative, one.sided = 1, two.sided = 2)
> - if (tside == 2 && !is.null(delta))
> + if (tside == 2)
> delta <- abs(delta)
> p.body <- quote({
> nu <- (n - 1) *...
2017 Dec 14
2
delta and sd parameters for power.t.test
What is the rationale behind having both the delta and sd parameters for
the power.t.test function? For the relevant noncentrality parameter, we
only need the ratio delta/sd. If my effect size is given as Cohen's d,
then I only got that ratio and not sd.
As far as I see, in such a case, I can specify delta=d and leave sd at
its default value 1. Is this correct or am I missing something?