. Author manuscript; available in PMC: 2010 Mar 24.

Published in final edited form as: Psychol Assess. 2008 Sep;20(3):206–216. doi: 10.1037/a0012764

Table 4. DSM–IV Generalized Anxiety Disorder Item-by-Item Tests for Effects of Age on Thresholds.

Model	−2LnL	Δχ²	Δdf	AIC	Age effect
Age on latent mean (baseline)	14,246.62			−14,567.38
Item free
Did your muscles often feel tense, sore or achy?	14,246.34	0.28	1	−14,565.66	.08
Did you often tire easily?	14,226.54	20.08^***	1	−14,585.45	−.74
Were you so nervous you had trouble concentrating?	14,246.18	0.44	1	−14,565.82	−.10
Did you often have trouble falling asleep?	14,245.93	0.69	1	−14,566.07	−.13
Were you often irritable or especially impatient?	14,227.42	19.21^***	1	−14,584.58	.73
Did you feel restless or keyed up and on edge?	14,246.50	0.12	1	−14,565.50	−.09

Note. N = 6,426. The most parsimonious model is shown in boldface. DSM–IV = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition; AIC = Akaike information criterion.

^***

p < .001.