TABLE 2.
Appraisal of the papers selected according to Downs and Black Appraisal Scale (n = 25).
| Authors | Reporting (n = 8) | External validity (n = 3) | Internal validity (n = 3) | Power (n = 1) | Total (n = 15) |
|---|---|---|---|---|---|
| Crtyzer et al. (2013) | 4 | 1 | 1 | 1 | 7/15 |
| Da Silva Alves et al. (2013) | 4 | 0 | 1 | 1 | 6/15 |
| De Groot et al. (2013) | 4 | 2 | 2 | 1 | 9/15 |
| Froehlich-Grobe et al. (2014) | 5 | 2 | 3 | 1 | 11/15 |
| Grogery et al. (2014) | 3 | 2 | 1 | 1 | 7/15 |
| Kressler et al. (2014) | 6 | 2 | 3 | 1 | 12/15 |
| Lu et al. (2014) | 4 | 1 | 1 | 1 | 7/15 |
| Oliveira et al. (2014) | 4 | 1 | 1 | 1 | 7/15 |
| Sprigle (2014) | 4 | 0 | 1 | 1 | 6/15 |
| Tanhoffer et al. (2014) | 4 | 2 | 2 | 1 | 9/15 |
| Van Straaten et al. (2014) | 5 | 1 | 2 | 1 | 9/15 |
| West et al. (2014) | 5 | 2 | 3 | 1 | 11/15 |
| Kim et al. (2015) | 5 | 2 | 3 | 1 | 11/15 |
| La Fountaine et al. (2015) | 5 | 2 | 2 | 1 | 10/15 |
| Thompson, Snodgrass and Osmotherly (2015) | 4 | 2 | 2 | 1 | 9/15 |
| Van Der Scheer et al. (2015) | 5 | 2 | 2 | 1 | 10/15 |
| Vosloo, Ntsiea and Becker (2015) | 6 | 2 | 2 | 1 | 11/15 |
| Will et al. (2015) | 4 | 2 | 3 | 1 | 10/15 |
| Wong et al. (2015) | 5 | 1 | 2 | 1 | 9/15 |
| Chen et al. (2016) | 5 | 2 | 3 | 1 | 11/15 |
| Nooijen et al. (2016) | 5 | 2 | 3 | 1 | 11/15 |
| Torhaug et al. (2016) | 5 | 2 | 3 | 1 | 11/15 |
| Tweedy et al. (2016) | 3 | 1 | 1 | 1 | 6/15 |
| Nightingale et al. (2017) | 4 | 1 | 1 | 1 | 7/15 |
| Ekelman et al. (2017) | 4 | 2 | 1 | 0 | 7/15 |
Source: Authors’ own work