Hello, I'm using the package survey, version 3.22-2 in R 2.11.1, on windows XP, but this isn't a platform issue. I am trying to calculate some regression and probability proportional to size (pps) estimates for a dataset I have. The data has 2 strata, weights, and cluster IDs. However, I can't find a way to use multiple strata in the svydesign function. Currently, I'm ditching the weights and using the second strata as a weighting mechanism (outlined below). surveyDesign<-svydesign(id=~EstID, strata=~strataOne, weights=~strataTwoMod, data=regressionData, nest=T) But that really doesn't meet the needs of this project. I've also tried it with strata=(~strataOne + strataTwo), but that didn't work either. Does anyone know if its a) possible to do mutiple strata sampling in R survey, and b) how? I emailed the maintainer a week ago, but I still haven't heard back. Thanks, -- Owen Gallagher President, Washington Society, Fall 2010 Treasurer, American Parliamentary Debate Association, 2010-2011 Computer Engineering, Class of 2011 School of Engineering and Applied Science, University of Virginia