Table 2.

Disease stage model comparison.

	AIC	Tested variable	df	N	X2	p
Groups ∼ TI	644.70	TI	2	445	172.78	<0.0001
Groups ∼ TSS	649.90	TSS	2	445	122.58	<0.0001
Groups ∼ TI + TSS	647.43	TI	2	445	51.47	<0.0001
–	–	TSS	2	445	1.27	0.53
Groups ∼ TI + TSS + TI × TSS	649.02	TI	2	445	14.90	0.00026
–	–	TSS	2	445	1.90	0.39
–	–	TI × TSS	2	445	2.41	0.30

Comparison of individual TI, individual TSS, additive, and interactive models predicting disease-stage group. Multinomial logistic regressions with covariates age and sex evaluated with likelihood ratio chi-square tests. Test statistics and significance reported for tested variables as well as evaluation of the model via AIC.

TI, Tau Index.

TSS, Tau Spatial Spread.

AIC, Akaike Information Criterion.

df, degrees of freedom.