Table 2.

Poisson model comparisons for males

	Any Eating Disorder		Anorexia Nervosa		Other Eating Disorder
	Deviance	DF	Deviance	DF	Deviance	DF
Model I. Agea	501.3	65	231.7	65	455.1	65
Model II. Agea + Period (drift)b	105.8	64	69.0	64	98.0	64
Model III. Agea + Periodc	67.6	58	47.9	58	58.6	58
Model IV. Agea + Cohortd	299.0	64	146.9	64	271.1	64
Model V. Agea + Period (drift)b + Cohortd	105.4	63	68.9	63	98.0	63
Model VI. Agea + Periodc + Cohortd	67.5	57	47.9	57	58.6	57
Model II vs. Model Ie	p < 0.001		p < 0.001		p < 0.001
Model III vs. Model IIe	p < 0.001		p = 0.002		p < 0.001
Model VI vs. Model IIIe	p = 0.84		p = 0.92		p = 0.85
Best-Fitting Model (overdispersion test)f	Model III (p = 0.70)		Model III (p = 0.99)		Model III (p = 0.99)

Abbreviations: DF = Degrees of Freedom

^aAge treated as categorical variable with levels for every year between 8 and 30 (inclusive). There is no reference level because model excludes an intercept term.

^bPeriod treated as an interval variable with the levels described in footnote c assigned integer values 0 – 10.

^cPeriod treated as categorical variable with levels [1987–1991] (reference level), [1992–1997], [1998–1999], [2000–2001], [2002–2003], [2004–2005], [2006–2007], [2008–2009].

^d(Birth) Cohort treated as categorical variable with levels [1979–1990] (reference level), [1991–2001].

^ep-value based on chi-squared test comparing (residual) deviance and DF for Model A (less reduced model) versus Model B (more reduced model).

^fp-value based on (one-sided) test of H_1. Poisson model mean < variance (overdispersion) versus H_0. mean = variance (no overdispersion).