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

VALUE:

TOTAL sample size(s)

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))