Frequencies for first 10,000 rows of blodpres variable in namcs1999 dataset : blood | pressure | test | Freq. Percent Cum. ------------+----------------------------------- 0 | 6,280 62.80 62.80 1 | 3,720 37.20 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016