The RePEc Author Service recently surpassed 15,000 registered authors, and the post relating this mentions the high coverage among top ranked economists. To document this, take one popular ranking, the one by Tom Coupé that is based on publications from 1990 to 2000. Tom Coupé has two rankings, one where publications are weighted by the impact factors of the journals, the other where citations are counted. According to the “publications” ranking, 75% of the 1000 economists are now registered with RePEc, according to the other 65%. The difference comes from the fact that the latter also includes non-economists (political scientists, statisticians, demographers, law scholars, and sociologists) that are cited in Economics journals.
One particularly interesting aspect of these rankings is how the proportions of registered authors decline with rankings:
| Ranks | registered, publication ranking |
registered, citation ranking |
| 1-100 | 93 | 77 |
| 101-200 | 81 | 72 |
| 201-300 | 78 | 69 |
| 301-400 | 73 | 76 |
| 401-500 | 77 | 66 |
| 501-600 | 71 | 61 |
| 601-700 | 73 | 54 |
| 701-800 | 77 | 55 |
| 801-900 | 62 | 62 |
| 901-1000 | 65 | 60 |
| Total | 750 | 652 |
How can we explain this pattern? Are registered authors more likely to publish well or be cited? This may be true for more recent measures of visibility, but in 1990-2000, the RePEc Author Service was not yet functional. Are then better ranked authors more likely to care more about their visibility and thus more likely to register?
The RePEc Blog 
An additional explanation is that older scholars tend to do better in citation rankings. They would be less likely to register.