Year Boys Girls
1977 1979 1981  Frequency Percent  Frequency Percent
O O O 897 36% 873 37%
O O M 318 13% 313 13%
O M O 88 4% 96 4%
O M  M 389 16% 367 15%
M  O O 317 12% 328 14%
M O M 196 8% 174 7%
M M  O 281 11% 219 10%
Note: `O' denotes observed measurement, `M' denotes missing measurement.
Table 1: Muscatine Coronary Risk Factor data: Frequency and percent of children per missing data pattern for boys and girls separately