Frequencies for first 10,000 rows of ekg variable in nhamcsopd2008 dataset : ekg/ecg | (electrocar | diogram) | Freq. Percent Cum. ------------+----------------------------------- no | 9,739 97.39 97.39 yes | 261 2.61 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016