Frequencies for first 10,000 rows of hematocr variable in namcs1998 dataset : hematocrit/ | hemoglobin | Freq. Percent Cum. ------------+----------------------------------- 0 | 9,388 93.88 93.88 1 | 612 6.12 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 28 Mar 2016