csdvsmdd.fisher {MDD}R Documentation

CSD vs. MDD for Fisher's Exact Test

Description

For a trial evaluated using Fisher's exact test, calculates the probabilities of either having a clinically significant difference declared statistically insignificant, or of having a statistically significant difference declared clinically insignificant. Also ouputs the power of the test.

Usage

csdvsmdd.fisher(n.placebo, n.treat, prob.placebo, prob.treat, csd, alpha = 0.05, 
                alternative = "two.sided")

Arguments

n.placebo number of subjects in control group.
n.treat number of subjects in treatment group.
prob.placebo anticipated proportion of responses in control group.
prob.treat anticipated proportion of responses in treatment group.
csd clinically significant difference.
alpha significance level.
alternative indicates the alternative hypothesis and must be one of "two.sided", "greater", or "less". You can specify just the initial letter.

Details

The “clinically significant difference” is the smallest difference that will be meaningful either clinically or commercially. This is usually obtained from the clinical scientists and/or business partners you are working with.

Value

A list with the following three components:

statsig.not.clinsig the probability that the trial will have a statistically significant but clinically insignificant result.
clinsig.not.statsig the probability that the trial will have a clinically significant but statistically insignificant result.
power the power of the test.

Author(s)

Don Barkauskas (barkda@wald.ucdavis.edu)

References

See fisher.test for references.

See Also

csdvsmdd.chisq for an asymptotic test

gui.csdvsmdd for a GUI version

Examples

csdvsmdd.fisher(36, 36, .25, .6, .25)

#Note that both possibilities are represented here.

csdvsmdd.fisher(20, 20, .25, .6, .25)
csdvsmdd.fisher(20, 20, .25, .6, .45)

#Compare to the same commands using csdvsmdd.chisq; the first leads to identical 
#results, while the second and third give different results.


[Package MDD version 0.5 Index]