| to the world | 9 | transitive-object |
| genetically | 8 | manner |
| in improving the types of grasses | 5 | other |
| bison → be → important | 10 |
| bison → play → important role | 6 |
| negative | neutral | positive |
| 0.097 | 0.545 | 0.358 |
| Raw frequency | 16 |
| Normalized frequency | 0.520 |
| Modifier score | 0.500 |
| Perplexity | 169.108 |