From: Categorisation of built environment characteristics: the trouble with tertiles
Model | Predictor | Coefficient | (S.E.) (a) | p-value | AIC (f) |
---|---|---|---|---|---|
Linear Model | Intercept | 26.43 | (0.35) | <0.001 | 9139.73 |
 | Count of supermarkets | −0.10 | (0.03) | <0.001 |  |
Fractional | Intercept | 26.53 | (0.37) | <0.001 | 9139.73 |
Polynomial(b) | (Count of supermarkets + 1)/10 | −1.00 | (0.27) | <0.001 |  |
Spline (2 knots)(c) | Intercept | 26.53 | (0.56) | <0.001 | 9141.66 |
 | 1st segment, 0—11 supermarkets | −1.25 | (0.69) | 0.068 |  |
 | 2nd segment, 11—15 supermarkets | −4.80 | (1.56) | 0.002 |  |
Spline (3 knots)(d) | Intercept | 25.39 | (0.68) | <0.001 | 9132.98 |
 | 1st segment, 0—9 supermarkets | 0.90 | (0.86) | 0.29 |  |
 | 2nd segment, 9—15 supermarkets | −1.11 | (0.71) | 0.12 |  |
 | 3rd segment, 15—50 supermarkets | 0.66 | (0.66) | 0.78 |  |
Tertiles(e) | 0—9 supermarkets (baseline) | 26.05 | (0.25) | <0.001 | 9137.67 |
 | 10—14 supermarkets | −1.00 | (0.34) | <0.001 |  |
 | 15— supermarkets | −1.49 | (0.36) | <0.001 |  |