Table II.
Simulated power for detecting a between-group difference using conditional logistic regression with stratification based on propensity scores (sample size per group = 500 for scenarios 1–6, and 500 in group 1 and 1500 in group 2 for scenarios 7–8, significance level: 0.05)
| Variable | Number of strata | Group 1 | Group 2 | Number of strata | Group 1 | Group 2 | |
|---|---|---|---|---|---|---|---|
| Scenario 1 | Scenario 2 | ||||||
| Distribution of PS | Beta(2,4) | Beta(7,1) | Beta(2,4) | Beta(7,1) | |||
| Binomial proportion for success | 0.1 | 0.1 | 0.1 + PS/2 | 0.1 + PS/2 | |||
| 5 10 15 20 30 |
0.05 0.05 0.05 0.05 0.05 |
5 10 15 20 30 |
0.13 0.05 0.05 0.05 0.05 |
||||
| Scenario 3 | Scenario 4 | ||||||
| Distribution of PS | Beta(4,2) | Beta (2,4) | Beta (4,2) | Beta(2,4) | |||
| Binomial proportion for success | 0.1 + PS/2 | 0.3 + PS/2 | 0.3 + PS/2 | 0.1 + PS/2 | |||
| 5 10 15 20 30 |
0.88 0.90 0.90 0.90 0.89 |
5 10 15 20 30 |
0.94 0.92 0.91 0.90 0.89 |
||||
| Scenario 5 | Scenario 6 | ||||||
| Distribution of PS | Beta(4,2) | Beta(7,1) | Beta(4,2) | Beta(7,1) | |||
| Binomial proportion for success | 0.25 + PS/2 | 0.1 + PS/2 | 0.1 + PS/2 | 0.2 + PS/2 | |||
| 5 10 15 20 30 |
0.74 0.76 0.76 0.76 0.75 |
5 10 15 20 30 |
0.79 0.74 0.73 0.72 0.72 |
||||
| Scenario 7 | Scenario 8 | ||||||
| Distribution of PS | Beta(4,2) | Beta(2,4) | Beta(4,2) | Beta(2,4) | |||
| Binomial proportion for success | 0.1 + PS/2 | 0.2 + PS/2 | 0.2 + PS/2 | 0.1 + PS/2 | |||
| 5 10 15 20 30 |
0.70 0.80 0.82 0.83 0.83 |
5 10 15 20 30 |
0.95 0.88 0.86 0.85 0.84 |
||||
PS – propensity score, Beta(α,β) – beta distribution with parameters α and β.