{smcl} {* 08feb2008}{...} {cmd:help uniquestrata} {hline} {title:Title} {p 4 8 2} {bf:uniquestrata -- Check that the specified variables collectively account for every observation} {title:Syntax} {p 8 17 2} {cmdab:uniquestrata} {it:varlist} {title:Description} {p 4 4 2} {cmdab:uniquestrata} takes a varlist of strata variables and calculates whether all combinations of the levels of those strata variables add up to the total number of observations--no more, no less. If not, the program returns error 9. {p 4 4 2} Mathematically, it simply multiplies together the number of distinct levels of each strata variable given in varlist and compares that to the number of observations in the dataset.