SUDAAN uses # PSUs - # strata to calculate degrees of freedom for overall and sub-population estimates. SUDAAN does not currently have a means of calculating the degrees of freedom using only those PSUs with at least 1 member of the sub-population. You can specify your own degrees of freedom in SUDAAN, however.   SAS 9.4 survey procedures have a switch/option to calculate # PSUs - #strata using only those PSUs with at least 1 member of the sub-population.   STATA uses # PSUs - #strata using only those PSUs with at least 1 member of the sub-population by default.   The issue with degrees of freedom and replicate-based variance estimation is more complex. SAS and STATA use the number of replicates (or # of replicates -1 ) as the default degrees of freedom. The R Survey package assumes an infinite number of degrees of freedom   Note that the default degrees of freedom for replicate-based variance estimation can be much higher than the corresponding degrees of freedom if using #PSUs - # strata among those PSUs with at least 1 member of the subpopulation.   You can specify your own degrees of freedom when using replicate-based variance estimation in all three software programs: SAS, STATA, and the R Survey package. ... View more