Frequencies for first 10,000 rows of blodpres variable in nhamcsopd2000 dataset : blood | pressure | test | Freq. Percent Cum. ------------+----------------------------------- 0 | 4,722 47.22 47.22 1 | 5,278 52.78 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016