mudiff.freq: Frequentist sample size determination for differences in...

Description Usage Arguments Details Value Note Author(s) References See Also Examples

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

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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:

when equal = TRUE, final sample sizes n1 = n2;
when equal = FALSE, final sample sizes (n1, n2) minimize the variance given a total of n1+n2 observations

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 Belisle

References

Joseph L, Belisle 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

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#  Suppose variance1 = 2, variance2 = 4
mudiff.freq(len=0.2, lambda1=1/2, lambda2=1/4)

Example output

[1] 2305 2305

SampleSizeMeans documentation built on May 1, 2019, 6:50 p.m.