| mudiff.freq {SampleSizeMeans} | R Documentation |
Frequentist sample size determination for differences in normal means
Description
The function mudiff.freq returns the required sample sizes
to get a confidence interval of given length and confidence level for the difference between two normal means.
Usage
mudiff.freq(len, lambda1, lambda2, level = 0.95, equal=TRUE)Arguments
len |
The desired total length of the confidence interval for the difference between the two unknown means | |||||||||
lambda1 |
Known precision (reciprocal of the variance) for the first population | |||||||||
lambda2 |
Known precision (reciprocal of the variance) for the second population | |||||||||
level |
The desired confidence level (e.g., 0.95) | |||||||||
equal |
logical. Whether or not the final group sizes (n1, n2) are forced to be equal:
|
Details
Assume that a random sample from each of two populations will be
collected in order to estimate the difference between two independent normal means.
Assume further that the two precisions lambda1 and lambda2 are known (where precision is the reciprocal of the variance).
The function mudiff.freq returns the required sample sizes to attain the
desired length len and confidence level level for the confidence interval
for the difference between the two unknown means from a frequentist point of view.
Value
The required sample sizes (n1, n2) for each group given the inputs to the function.
Note
The sample sizes returned by this function are exact.
Author(s)
Lawrence Joseph lawrence.joseph@mcgill.ca and Patrick Bélisle
References
Joseph L, Bélisle P.
Bayesian sample size determination for Normal means and differences between Normal means
The Statistician 1997;46(2):209-226.
See Also
mudiff.acc, mudiff.alc, mudiff.modwoc, mudiff.acc.equalvar, mudiff.alc.equalvar, mudiff.modwoc.equalvar, mudiff.varknown, mudiff.mblacc, mudiff.mblalc, mudiff.mblmodwoc, mudiff.mblacc.equalvar, mudiff.mblalc.equalvar, mudiff.mblmodwoc.equalvar, mudiff.mbl.varknown, mu.freq, mu.acc, mu.alc, mu.modwoc, mu.varknown, mu.mblacc, mu.mblalc, mu.mblmodwoc, mu.mbl.varknown
Examples
# Suppose variance1 = 2, variance2 = 4
mudiff.freq(len=0.2, lambda1=1/2, lambda2=1/4)