Table 4.
Positive Predictive Value of 4 different measures of bullying
| “ Gold standard” definition | Definition+‘bully’ | Definition-only | ‘Bully’-only | Definition+‘bully’+‘harassment’ | All (combined) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||||||||
| < monthly | monthly+ | PPV | < monthly | monthly+ | PPV | < monthly | monthly+ | PPV | < monthly | monthly+ | PPV | < monthly | monthly+ | PPV | |
| Three criteria met a | |||||||||||||||
| Yes | 3% (8) | 9% (22) | 18 % | 0% (1) | 11% (39) | 17% | 1% (4) | 10% (25) | 17 % | 2% (6) | 11% (32) | 22% | 2% (19) | 10% (118) | 18% |
| No | 31% (96) | 13% (39) | 25% (87) | 44% (110) | 31% (94) | 15% (47) | 32% (88) | 14% (50) | 30% (365) | 21% (246) | |||||
| Differential power b | |||||||||||||||
| Yes | 12% (39) | 14% (36) | 59 % | 10% (30) | 22% (70) | 47% | 14% (43) | 17% (47) | 65 % | 13% (37) | 16% (50) | 61% | 12% (149) | 17% (203) | 56% |
| No | 22% (65) | 8% (25) | 16% (58) | 33% (79) | 18% (55) | 8% (25) | 21% (57) | 9% (32) | 19% (235) | 14% (161) | |||||
Percentages are based upon the entire sample. For example, 3% of all youth in the Definition + bully study reported being bullied less than monthly and also met all three criteria. Percentages for youth who did not report being bullied can be calculated by subtracting the four shown groups of youth from 100%.
PPV=Positive predictive value, calculated as the true positives/(true positives + false positives).
The ‘gold standard’ is the measure (either <monthly or monthly+) + all three criteria met (i.e., [1] differential power, [2] repetition, and [3] over time).
For example, definition+‘bully’ PPV for all three criteria = (22+8)/(22+8+96+39).
The ‘gold standard’ is frequency of ‘monthly’ or more often + differential power.
For example, definition+‘bully’ PPV for all three criteria = (36)/(36+25).