Table 3.
Simulation Results Based on a True Net Monetary Benefit Value of £1000 at a Cost-Effectiveness Threshold of £20,000 per Quality-Adjusted Life-Year
| Simulation Parameters and Method | Mean (SE) Bias, £ | 95% CI Coverage | RMSE, £ |
|---|---|---|---|
| Base case simulation (N = 200 from 10 clusters each of size 20, CV = 0.5 for costs and effects, ICCcosts = 0.05, ICCeffects = 0.02) | |||
| Stata gsem, ml vce robust | 5.85 (13.57) | 0.93 | 331.13 |
| Stata mixed, ml vce robust via pql | 3.00 (13.53) | 0.93 | 329.87 |
| Stata mixed, reml via pql | 1.31 (13.49) | 0.95 | 329.09 |
| R lme, ml via pql | 2.78 (13.52) | 0.94 | 329.79 |
| R lme, reml via pql | 1.11 (13.49) | 0.96 | 329.04 |
| Scenario 1 (base case with no. of clusters changed from 10 to 5) | |||
| Stata gsem, ml vce robust | 6.40 (26.04) | 0.82 | 481.54 |
| Stata mixed, ml vce robust via pql | 3.91 (25.97) | 0.81 | 480.22 |
| Stata mixed, reml via pql | 4.71 (25.9) | 0.96 | 479.11 |
| R lme, ml via pql | 3.94 (25.97) | 0.93 | 480.33 |
| R lme, reml via pql | 4.64 (25.9) | 0.96 | 479.11 |
| Scenario 2 (base case with cluster size changed from 20 to 50) | |||
| Stata gsem, ml vce robust | 0.43 (10.14) | 0.92 | 265.5 |
| Stata mixed, ml vce robust via pql | −1.26 (10.12) | 0.92 | 265.0 |
| Stata mixed, reml via pql | −2.14 (10.11) | 0.94 | 264.7 |
| R lme, ml via pql | −1.44 (10.12) | 0.91 | 264.9 |
| R lme, reml via pql | −2.20 (10.11) | 0.94 | 264.7 |
| Scenario 3 (base case with CV changed from 0.5 to 1.0 for both costs and effects) | |||
| Stata gsem, ml vce robust | 13.77 (23.42) | 0.93 | 593.9 |
| Stata mixed, ml vce robust via pql | 4.73 (23.19) | 0.93 | 588.2 |
| Stata mixed, reml via pql | 0.47 (23.09) | 0.94 | 585.9 |
| R lme, ml via pql | 4.42 (23.18) | 0.93 | 588.1 |
| R lme, reml via pql | 0.31 (23.09) | 0.94 | 585.9 |