Table 4.
Parameter Estimates for Average Labor Costs per Visit per Practice Year Estimated from Random Intercept Linear Regression of Year Nested within Practice
| Per Visit Costs | ||||
|---|---|---|---|---|
| Practitioner Costs | Total Costs | |||
| β | P | β | P | |
| Intercept | $26.18 | <.01 | $38.57 | <.01 |
| Predicted percent of PA/NP visits (per 10% increments)*† | −1.02 | <.01 | −0.79 | .08 |
| Visits per practice year (per 1,000 visit increments) | −0.11 | .10 | −0.26 | .01 |
| Adult medicine | −3.19 | <.01 | −4.89 | <.01 |
| Mean practitioner tenure (per year)† | 0.45 | .06 | 0.54 | .08 |
| 1998 | 0.84 | .18 | 1.85 | .04 |
| 1999 | 0.91 | .17 | 3.43 | <.01 |
| 2000 | 2.97 | <.01 | 6.13 | <.01 |
| ICC | 0.524 | 0.489 | ||
| Model chi-square | 63.3‡ | 94.1‡ | ||
| Number of practice years | 104 | 104 | ||
*
Expected percent per practice year computed using the logistic regression parameter estimates by year, the population case mix for the year, and the practice-specific propensity to use PAs/NPs in primary care delivery.
†
Variables are centered at the practice means (Table 3).
‡
Significant for p<.01, df=7.