# Sample size calculation for test size alph, power pow, odds
# ratio odd, and probability of success at xbar P.  If size
# or power are input as percentages, they are converted to
# proportions
lregss=function(alph,pow,odd,P){
if(alph>1) alph=alph/100
if(pow>1) pow=pow/100
tauhat=log(odd)
za=qnorm(1-alph)
zb=qnorm(pow)
n1=(za+zb*exp(-tauhat^2/4))^2/(P*tauhat^2)
delt=(1+(1+tauhat^2)*exp(5*tauhat^2/4))/(1+exp(-tauhat^2/4))
n2=n1*(1+2*P*delt)
out=list("Odds Ratio"=odd,"P"=P,"Sample Size"=n2)
out
}