An index identifying factors leading to unusual response patterns by students, the modified caution index, was computed for the reading comprehension and study skills items of Booklet 5 from the 1979 National Assessment of Educational Progress (NAEP) reading achievement survey given to the 9-, 13- and 17-year-old samples. The analyses focused on reporting student and school variables associated with unusual response patterns (high modified caution indices). The findings were compared to the results of a similar study which examined 13-year-olds' performance on the 1978 NAEP mathematics survey. Taken together, these studies provide a description of the relationship between the characteristics of students and their response patterns to a selection of items used to survey mathematics and reading performance levels in the United States. This description helps to illustrate how response pattern analyses conducted within local school settings can be used to identify individual students inadequately prepared for test material, as well as groups of students (classrooms) for whom content coverage was not consistent with specified instructional objectives. (PN)