Frequencies for first 10,000 rows of telephon variable in nhamcsopd1994 dataset : telephone | follow-up | planned | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,666 96.66 96.66 1 | 334 3.34 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016