| Data collection method | N | Percentage |
| Interview | 14 | 61% |
| Observation | 8 | 35% |
| Survey | 8 | 35% |
| Questionnaire | 7 | 31% |
| Focus group | 4 | 18% |
| Document analysis | 4 | 18% |
| PIMRS | 1 | 4% |
| School principal scale | 1 | 4% |
| Whistle blowing scale | 1 | 4% |
| Shared leadership perception scale | 1 | 4% |
| Distributed leadership scale | 1 | 4% |
| Total studies | 23 | 100% |