samplesize.bin {Hmisc} | R Documentation

## Sample Size for 2-sample Binomial

### Description

Computes sample size(s) for 2-sample binomial problem given vector or scalar probabilities in the two groups.

### Usage

    samplesize.bin(alpha, beta, pit, pic, rho=0.5)

### Arguments

`alpha` | scalar ONE-SIDED test size, or two-sided size/2
`beta` | scalar or vector of powers
`pit` | hypothesized treatment probability of success
`pic` | hypothesized control probability of success
`rho` | proportion of the sample devoted to treated group (0 <rho < 1)

### Value

TOTAL sample size(s)

### AUTHOR

Rick Chappell

Dept. of Statistics and Human Oncology

University of Wisconsin at Madison

chappell@stat.wisc.edu

### Examples

    alpha <- .05
    beta <- c(.70,.80,.90,.95)

    # N1 is a matrix of total sample sizes whose
    # rows vary by hypothesized treatment success probability and
    # columns vary by power
    # See Meinert's book for formulae.

    N1 <- samplesize.bin(alpha, beta, pit=.55, pic=.5)
    N1 <- rbind(N1, samplesize.bin(alpha, beta, pit=.60, pic=.5))
    N1 <- rbind(N1, samplesize.bin(alpha, beta, pit=.65, pic=.5))
    N1 <- rbind(N1, samplesize.bin(alpha, beta, pit=.70, pic=.5))
    attr(N1,"dimnames") <- NULL

    #Accounting for 5% noncompliance in the treated group
    inflation <- (1/.95)**2
    print(round(N1*inflation+.5,0))

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