Characteristics of the Study Group
Demographic findings. A total of 19 schools distributed the assessment instruments, which were completed by 3,218 students.
Table 1 identifies the distribution of student participants by gender, race/ethnicity, and grade level. Girls (N=1,760, 56.5%) outnumbered boys (N=1,354, 43.5%), while the actual enrollment of boys and girls in the school district was more even. The racial/ethnic distribution of the study group roughly paralleled school-wide distribution, with 43.7% self-reporting as African American, 34.9% as Anglo, 11.6% as Hispanic, 4.4% as American Indian, and 5.4% as other. While the racial/ethnic distribution for the specific schools in which participants were enrolled is unavailable, the distribution for the total Oklahoma City Public School District student body (elementary, middle, and high schools) during the 1994–1995 school year was 40.7% African American, 38.5% Anglo, 12.7% Hispanic, 5.2% American Indian, and 2.9% Asian American. Youths were categorized not by age but by grade level as either middle or high school students. A preponderance of the study group was at the middle school level (N=2,360, 75.8%). Discrepancies in study group sizes in various categories reflect missing data.
Physical proximity and exposure. The majority (N=2,729, 84.9%) of the total study group reported being in school on the day of the bombing. Over 60% of the students reported hearing (N=1,979, 61.5%) and/or feeling (N=1,988, 61.8%) the blast. For 746 students (23.2%), it was “very loud,” and for 758 students (23.6%), it felt “very strong.” Television exposure was also extensive; over two-thirds (N=2,137, 66.6%) of the participants reported that “most” or “all” of their television viewing was bomb related (“most”: N=1,368, 42.6%; “all”: N=769, 24.0%).
Personal loss and consequences. A surprisingly large number of youths experienced exposure by knowing someone injured or killed in the blast.
Table 2, combining middle and high school students, identifies reported exposure to injury or death by relationship. Three hundred thirty students reported attending at least one bomb-related funeral; of these, 107 attended more than one funeral.
Fear and arousal. The results indicate strong reactions at the time of the blast for students throughout the district. A sizable number of students reported perceived life threat (N=431, 13.5%) and physiological arousal at the time of the bombing (
Table 3). About two-thirds (N=2,135, 67.0%) reported worrying for the safety of a family member, over one-half (N=1,861, 58.4%) reported worrying for the safety of a friend, and over 40% (N=1,285, 40.6%) reported feeling helpless. At the time of the assessment, 7 weeks after the bombing, 464 (14.6%) of the students reported that they still did “not feel safe at all,” and 1,084 (34.1%) reported worrying about themselves or their families.
Characteristics of the Exposed and Nonexposed Groups
The mean posttraumatic stress symptom scores were examined with respect to the amount of bomb-related television viewing in the exposed group (F=49.25, df=4, 2991, p=0.0001). The highest mean posttraumatic stress symptom score (mean=46.2, SD=13.6) was in the group reporting that “all” of their television viewing was bomb related. This group’s mean score was significantly higher than those of all other groups (Duncan’s multiple range test, p<0.05) (
Table 4).
The mean posttraumatic stress symptom score in the exposed group was also examined in relation to personal loss and its consequences. With respect to reporting knowing someone injured (F=26.14, df=5, 2995, p=0.0001), mean posttraumatic stress symptom scores were highest for those reporting sibling injured (mean=51.0, SD=7.9), followed by those reporting parent injured (mean=47.4, SD=11.5). Those reporting a sibling injured had significantly higher mean posttraumatic stress symptom scores than all other groups (Duncan’s multiple range test, p<0.05) (
Table 4).
The posttraumatic stress symptom analysis was examined by reported relationship to those killed in the blast for those in the exposed group (F=27.86, df=5, 2990, p=0.0001). Those reporting a sibling killed had the highest mean posttraumatic stress symptom scores (mean=49.0, SD=10.0), followed by those reporting a parent killed (mean=48.8, SD=11.4).
The two-by-two factorial (exposure group and gender) analysis revealed no significant interactions. The analysis did show a significant main effect of exposure and gender (
Table 5). The exposed group had significantly higher scores than the nonexposed group. The girls had significantly higher scores than the boys.
When the total study group was used, stepwise regression analysis was performed with the posttraumatic stress symptom as the criterion variable and gender, race/ethnicity, grade level, and exposure as predictors. Before step one, the primary predictor of posttraumatic stress symptom was exposure. This variable accounted for 11% of the variance, with the other three variables each accounting for less than 3% of the variance. Therefore, step one included the exposure variable in the model. In exploring the remaining variance, we found that gender accounted for an additional 12% of the variance. The other two variables—grade level and race/ethnicity—accounted for only slightly less (11% each) before step two, the inclusion of gender in the model. Grade level, accounting for 13% of the remaining variance, entered the model at step three, unaffected by the removal of the variance accounted for by gender. The dummy coded race/ethnicity variable, while accounting for only slightly less variance than gender in step two and grade level in step three, did not enter the equation at any step. The overall model met statistical significance (F=143.56, df=3, 2891, p=0.0001) and accounted for 13% of the variance in the posttraumatic stress symptom scores. In the overall model, exposure accounted for the majority of the variance (11% of 13%). It should be noted that bomb-related television viewing contributed to exposure and therefore was not entered as a separate item.
In the final analyses, a stepwise linear regression analysis was used to build a predictive model for posttraumatic stress symptom scores from gender, race/ethnicity, grade level, and amount of bomb-related television viewing. The first variable that entered the model was bomb-related television viewing, accounting for 7% of the variance (R2=0.07). Other variables accounted for far less of the variance before the inclusion of the television exposure variable (less than 3%). After the inclusion of television exposure, gender was the most strongly related variable (R2=0.08). Although the other two variables accounted for only slightly less of the remaining variance, gender was chosen by the procedure. Finally, the last variable to enter the model at a statistically significant level was the grade level variable (R2=0.08). Inclusion of gender in step two had little effect on the amount of variance accounted for by grade level. As in the previous analyses, the race/ethnicity variable never entered the model. The final model, including the three contributing variables, was significant (F=88.45, df=3, 2942, p=0.0001), accounting for 8% of the total variance. When the entire model was reviewed, television exposure accounted for most of the variance (R2=0.07). The addition of the other two variables improved the predictive model less than 2%.