| Researcher | Year | Criteria | Grade | |||||
| Goals and objectives | Study context | Sample | Methodology | Data | The results of the study are validated | |||
| | 2017 | / | / | / | / | / | / | A |
| | 2016 | / | / | / | / | / | / | A |
| | 2013 | / | / | / | / | / | / | A |
| | 2018 | / | / | / | / | / | / | A |
| | 2015 | / | / | / | / | / | / | A |
| | 2009 | / | / | / | / | / | / | A |
| | 2018 | / | / | / | / | / | / | A |
| | 2016 | / | / | / | / | / | / | A |
| | 2018 | / | / | / | / | / | / | A |
| | 2016 | / | / | / | / | / |
| B |
| | 2017 | / |
| / | / | / | / | B |
| Jane & Daniel | 2019 | / |
| / | / | / | / | B |
| | 2016 | / | / |
| / | / | / | B |
| | 2013 | / |
| / | / | / |
| C |
| Hart Research Associates | 2015 | / |
| / | / | / |
| C |
| | 2016 | / |
| / | / | / |
| C |
| | 2016 | / |
| / | / | / |
| C |