Frequencies for first 10,000 rows of blodpres variable in nhamcsopd2010 dataset : blood | pressure | taken | Freq. Percent Cum. ------------+----------------------------------- no | 3,712 37.12 37.12 yes | 6,288 62.88 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016