Table II.

Functions f(x) and w(ℓ), total degrees of freedom (df) associated with the cross-basis, and values for the AIC and BIC for alternative models for the exposure–lag–response association between radon and mortality. Data from the Colorado Plateau uranium miners cohort

DLMs
	f(x)	w(ℓ)	df	AIC	BIC
Model 1	Linear	Constant	1	2236.0	2257.3
Model 2	Linear	Piecewise constant†	4	2238.6	2270.6
Model 3	Linear	Quadratic B-Spline‖	4	2238.8	2270.8
Model 4	Linear	Quadratic B-Spline§	3	2238.9	2267.3

DLNMs
	f(x)	w(ℓ)	df	AIC	BIC
Model 5	Quadratic B-Spline*	Constant	3	2181.4	2209.8
Model 6	Piecewise constant‡	Piecewise constant†	12	2171.6	2232.0
Model 7	Quadratic B-Spline*	Quadratic B-Spline‖	12	2155.3	2215.7
Model 8	Quadratic B-Spline*	Quadratic B-Spline§	9	2153.2	2202.9

^‡Cut-offs at 26.7, 60.2, and 122.2 WLM/years.

^†Cut-offs at 10, 20, and 30 lag.

^*Knot at 60.2 WLM/years.

^∥Knot at 13.3 lag.

^§Knot at 13.3 lag, no intercept.

DLM, distributed lag models; DLNMs, distributed lag non-linear models.