| Keyword | CPC | PCC | Volume | Score | Length of keyword |
|---|---|---|---|---|---|
| threats to external validity | 0.84 | 0.4 | 679 | 97 | 28 |
| threats | 1.22 | 0.3 | 2720 | 9 | 7 |
| to | 1.9 | 0.3 | 4552 | 55 | 2 |
| external | 1.82 | 1 | 6288 | 62 | 8 |
| validity | 0.64 | 0.2 | 9071 | 48 | 8 |
| Keyword | CPC | PCC | Volume | Score |
|---|---|---|---|---|
| threats to external validity | 1.13 | 0.2 | 6211 | 75 |
