| Variables | Frequency | Percentage |
| Type of studies |
|
|
| Quantitative studies | 10 | 45.5 |
| Qualitative studies | 11 | 50 |
| Mixed method study | 1 | 4.5 |
| Data collection tools |
|
|
| Questionnaire | 10 | 45.5 |
| In depth interview | 4 | 18.1 |
| Focus group discussion | 6 | 27.3 |
| Questionnaires and screening | 1 | 4.5 |
| Test | 1 | 4.5 |
| Unknown |
|
|
| Sampling methods |
|
|
| Convenience | 4 | 18.1 |
| Snowball | 5 | 22.7 |
| Purposive | 11 | 50 |
| Random | 1 | 4.5 |
| Stratified | 1 | 4.5 |