Table S1.

Cost models: (goodness of fit and ordinary least squares [robust])

Regression models	Incremental effect on cost	95% CI max	95% CI min	AIC
Local costings
OLS (robust)	−£2,746.58	−£4,899.02	−£594.14	19.39
GLM (Gaussian-Log)	−£3,291.65	−£4,952.08	−£2,104.93	19.36
GLM (Gamma-ID)	−£2,589.00	−£4,676.21	−£501.80	20.19
GLM (Gamma-Log)	−£2,824.93	−£5,266.25	−£2,153.15	20.20
GLM (Inverse Gaussian-ID)	−£2,671.19	−£4,531.63	−£810.75	28.69
GLM (Inverse Gaussian-Log)	−£3,196.00	−£20,881.79	−£2,109.59	28.69
GLM (Poisson-ID)	−£2,609.35	−£2,667.73	−£2,550.97	1243.50
GLM (Poisson-Log)	−£2,970.33	−£4,794.18	−£2,083.05	1232.81
National NHS costing
OLS (robust)	−£2,715.33	−£4,849.77	−£580.88	19.37
GLM (Gaussian-Log)	−£3,244.57	−£4,865.83	−£2,093.79	19.35
GLM (Gamma-ID)	−£2,557.90	−£4,635.49	−£480.31	20.21
GLM (Gamma-Log)	−£2,790.23	−£5,155.18	−£2,134.29	20.21
GLM (Inverse Gaussian-ID)	−£2,631.80	−£4,480.63	−£782.97	28.72
GLM (Inverse Gaussian-Log)	−£3,051.61	−£16,820.11	−£2,118.51	28.72
GLM (Poisson-ID)	−£2,580.16	−£2,638.81	−£2,521.51	1214.53
GLM (Poisson-Log)	−£2,933.00	−£4,712.09	−£2,069.84	1204.22

Abbreviations: AIC, Akaike information criterion; GLM, generalized linear model; NHS, National Health Service; OLS, ordinary least squares.