Table 11.
Multiple meta-regression analysis, predicting between-study variance in the success of blinding using the level of similarity between active and sham control groups for a number of selected features in all trials where Bang blinding index could be calculated (8 spinal manipulation trials, 7 other manual therapy, 1 physiotherapy and rehabilitation exercise, and 1 Reiki intervention).
| Descriptives | |||||||
|---|---|---|---|---|---|---|---|
| Mean ES | Mean (SD) similarity rating (sensations) | Mean (SD) similarity rating (application mode) | R 2 | k | |||
| 1.32 | 1.24 (1.15) | 1.71 (0.99) | 0.35 | 17 | |||
| Homogeneity analysis | |||||||
|---|---|---|---|---|---|---|---|
| Q | df | P | T 2 | I2 | |||
| Model | 8.92 | 2 | 0.0116 | 0.008 | 77.6% | ||
| Residual | 16.48 | 14 | 0.2847 | 0.003 | 15.1% | ||
| Total | 25.4 | 16 | 0.0631 | ||||
| Regression coefficients | |||||||
|---|---|---|---|---|---|---|---|
| B | SE | −95% CI | +95% CI | Z | P | Beta | |
| Constant | 3.0 | 0.87 | 1.27 | 4.7 | 3.42 | 0.0006 | 0.0 |
| Similarity: sensations | −0.97 | 0.52 | −2.0 | 0.05 | −1.87 | 0.06 | −0.5 |
| Similarity: application mode | −0.28 | 0.6 | −1.46 | 0.91 | −0.46 | 0.65 | −0.12 |
| Method of moments random effects variance component | |||||||
| v = 3.09 | |||||||
Means and variance of the similarity ratings included in the model are provided, having a possible range of −2 (different for all studies) to 2 (similar across all studies).