TABLE 5.
Model number | Description | Equation | β1 | β2 | β3 | Deviance | Referent model | P valuea |
---|---|---|---|---|---|---|---|---|
1 | Baselineb | αc | _ | _ | _ | 1532.5 | ||
2 | Linear | α + β1d | 0.458 | _ | _ | 1478.1 | 1 | <0.001 |
3 | Quadratic | α + β1d 2 | 0.00805 | _ | _ | 1516.1 | 1 | <0.001 |
4 | Linear exponential | α + β1d × exp(β2d) | 2.547 | −0.0582 | _ | 1439.8 | 2 | <0.001 |
5 | Linear exponential quadratic model-1 | α + β1d × exp(β2d2) | 1.830 | −0.00151 | _ | 1429.4 | 2 | <0.001 |
6 | Linear exponential quadratic model-2 | α + β1d × exp(β2d + β3d2) | 0.759 | 0.100 | −0.00381 | 1425.0 | 5 | 0.04 |
7 | Linear quadratic | α + β1d + β2d2 | 1.030 | −0.0156 | _ | 1448.9 | 2 | <0.001 |
8 | Linear quadratic exponential | α + (β1d + β2d2) × exp(β3d) | 2.351 | −0.0370 | −0.0327 | 1436.5 | 7 | <0.001 |
9 | Linear quadratic exponential quadratic | α + (β1d + β2d2) × exp(β3d2) | 0.284 | 0.169 | −0.00270 | 1424.1 | 5 | 0.02 |
10 | Quadratic exponential quadratic | α + β1d2 × exp(β2d2) | 0.197 | −0.00284 | 1424.3 | 3 | <0.001 |
Note. Italics represent the most parsimonious models with the lowest deviance and compatibility with radiobiological theory.
Likelihood ratio test comparing to referent model.
Baseline function includes natural logarithm of attained age, sex and type of childhood cancer (Hodgkin lymphoma, leukemia or other).
α represents the baseline function as described in footnote b.