Table 5.
Polynomial regression analyses on average individual costs per annum against the hyperactivity score (full sample N = 234)
| Predictor | β coefficient | Robust SE | p | CI (95%) |
|---|---|---|---|---|
| WWP score linear | 49.80 | 17.25 | .004 | (16.0 to 83.6) |
| WWP scorepolynomial | −0.86 | 0.37 | .020 | (−1.6 to −0.1) |
| Gender (male) | 426.88 | 138.08 | .002 | (156.2 to 697.5) |
| Age | −35.28 | 17.61 | .045 | (−69.8 to −0.8) |
| Conduct problems | 33.37 | 57.95 | .565 | (−80.2 to 147.0) |
| Emotional problems | 77.10 | 82.94 | .353 | (−85.5 to 239.7) |
| Deprivation | 4.63 | 24.04 | .847 | (−42.5 to 51.8) |
| Constant | 117.92 | 283.80 | .678 | (−438.3 to 674.1) |
Fitting a polynomial regression model to data points. The outcome variable is average individual costs per annum and input variables include baseline predictors with hyperactivity as a continuous variable. This model is similar to the model at the top of Table 4 but differs in terms of including WWP score as both a linear and a polynomial term to depict nonlinearity of the association between cost and WWP score.