I am working with some CDC weighted survey data (specifically YRBSS). The CDC has a website that displays the proportion of respondents who respond positively to the survey questions. The results are broken down by sex, school grade, and race. In each cell there is a proportion and a confidence interval. CDC says that the confidence intervals were produced by SUrvey DAta ANalyzer (SUDAAN).
The task at hand is to reproduce these confidence intervals using the R survey package. I have used the svymean function, and it gives the correct proportions, but different confidence intervals. It is important that we get the same CIs up to 4 or 5 decimals places, and we are not close. I have noticed that the SUDAAN CIs are not symmetric about the mean. This reminds me of logistic regression, but I don't know where to take it from there.
Can anybody give me a hand?