# reproducing SUDAAN confidence intervals with R survey package

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?

• Define your acronyms please. Otherwise, many of us, me especially, do not understand. – Carl Oct 30 '16 at 22:20
• CDC is the Center for Disease Control. YRBSS is a particular survey, specifically, Youth Risk Behavior Surveillance System or similar. SUDAAN is a software package for survey data from RTI International. RTI stands for nothing, but used to stand for Research Triangle Institute. SUDAAN? Probabiy SUrvey DAta ANalyzer or the like. – Rex D Oct 30 '16 at 22:27
• OK, help the reader by putting in links and using full text before citing acronyms as you will see shortly in my edit of your text: complete for CDC etc. There is acronym overload on this site. Yesterday, someone used "MLP", which unless you know a lot about machine learning looks like "my little pony." – Carl Oct 30 '16 at 22:43
• Carl, thanks for your interest. The author of the survey package has suggested that I look at the svyciprop function. What is MLP? – Rex D Oct 31 '16 at 1:21
• Yes, thus the acronym problem. "Multilayer perceptron" – Carl Oct 31 '16 at 2:25

In version 3.31-3 or later, I have added an option method="xlogit" to svyciprop() that appears to reproduce the SUDAAN results.
The intervals should be almost identical to those from method="logit", which is available in earlier versions of the package.