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