Frequencies for first 10,000 rows of mri variable in nhamcsopd2010 dataset : mri | Freq. Percent Cum. ------------+----------------------------------- no | 9,862 98.62 98.62 yes | 138 1.38 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016