one out of "wald", "waldcor", "ac", "exact", "newcombe", "newcombecor", "fm", "ha".
Value
A vector with 3 elements for estimate, lower confidence intervall and upper for the upper one.
Details
Still to follow.
References
Fagerland M W, Lydersen S and Laake P (2011) Recommended confidence intervals for two independent binomial proportions, Statistical Mehtods in Medical Research 0(0) 1-31
http://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#statug_freq_a0000000642.htm#statug.freq.freqbincp