Table 1. Pooled Prevalence Estimates and Proportion of Variance Explained by Methodological Factors (N = 43).
| Overall Effect size | Between Study Heterogeneity | ||||||
|---|---|---|---|---|---|---|---|
| Category2 | Pooled prev % | 95% CI | Z1 | Cochran Q | df (Q) | p | I2% |
| Anonymity | 7.9 | 2.9–20.1 | -4.5*** | 18.6 | 1 | .000 | 94.6 |
| Yes (n = 30) | 12.8 | 10.2–16.0 | -14.4*** | ||||
| No (n = 13) | 4.7 | 3.1–7.0 | -14.1*** | ||||
| Incentive type | 5.4 | 1.8–14.8 | -5.0*** | 19.1 | 2 | .000 | 90.1 |
| Course credit (n = 34) | 12.1 | 9.6–15.3 | -14.6*** | ||||
| None (n = 5) | 3.9 | 2.0–7.6 | -8.9*** | ||||
| Cash (n = 4) | 2.7 | 1.1–6.5 | -7.7*** | ||||
| Focus of research | 9.0 | 5.3–14.7 | -8.0*** | 4.6 | 1 | .032 | 78.6 |
| BPD (n = 29) | 11.4 | 8.7–14.7 | -13.6*** | ||||
| Other (n = 14) | 6.7 | 4.4–10.0 | -11.8*** | ||||
| Participant type | 17.6 | 6.2–40.9 | -2.6** | 8.1 | 2 | .017 | 75.3 |
| Postgraduates (PG; n = 1) | 32.1 | 8.9–69.5 | -0.9* | ||||
| UG & PG (n = 2) | 25.4 | 10.0–50.7 | -1.9 | ||||
| Undergraduates (UG; n = 40) | 8.9 | 7.1–11.1 | -18.3*** | ||||
| Data collection format3 | 7.9 | 3.9–15.3 | -6.4*** | 3.7 | 1 | .054 | 73.0 |
| Incentive4 | 8.3 | 4.6–14.5 | -7.5*** | 3.2 | 1 | .072 | 68.8 |
| Type of Measure5 | 9.4 | 5.9–14.6 | -8.7*** | 27.5 | 13 | .011 | 52.7 |
| IPDE6 (n = 4) | 21.6 | 17.0–27.0 | -4.8*** | ||||
| MSI-BPD7 (n = 5) | 13.6 | 7.4–23.7 | -5.3*** | ||||
| PAI-BOR8 (n = 20) | 9.3 | 6.8–12.7 | -12.9*** | ||||
| Construct measured9 | 8.2 | 4.9–13.5 | -8.5*** | 5.7 | 3 | .129 | 47.4 |
| Measure format10 | 10.1 | 7.4–13.6 | -12.7*** | 2.8 | 4 | .591 | 42.9 |
| Criterion measured11 | 9.4 | 6.5–13.3 | -11.3*** | 3.2 | 2 | .198 | 37.5 |
| Time period 12 | 11.5 | 5.8–21.6 | -5.4*** | 2.3 | 2 | .318 | 30.0 |
Note.
* p < .05
** p < .01
*** p < .001
1 Random effects analysis reported, ranked by I2
2 Only categories with significant heterogeneity (bold) have sub-levels reported (in italics)
3 Self-report or clinical interview
4 Incentive: yes/no
5 Type of measure only reported where measure n ≥4
6 The International Personality Disorder Examination
7 McLean Screening Instrument for Borderline Personality Disorder
8 Personality Assessment Inventory, Borderline Features Scale
9 Features, symptoms or traits of BPD
10 3,4 or 5-point scale, true/false or yes/no
11 Frequency, presence, severity or veracity (true/false) of BPD items
12 One month, 14 days, or life