Table of net ingredient cost (NIC) quintile minus prevalence quintile
| Difference | –4 | –3 | –2 | –1 | 0 | 1 | 2 | 3 | 4 |
| Number | 29 | 209 | 663 | 1628 | 3193 | 1456 | 648 | 217 | 68 |
| Proportion | 0.004 | 0.026 | 0.082 | 0.201 | 0.394 | 0.180 | 0.080 | 0.027 | 0.008 |
Positive (negative) differences correspond to practices whose NIC falls in a higher (lower) quintile than their reported prevalence.