Table 4.

χ², df and p for models 0 to 4. Differences between these models are used to test hypotheses of main effects and interactions)

Model	χ2 (df)	p
1 (b = d, a = c = 0)	358.25 (3)	<0.0001
2 (a = c = 0)	357.52 (2)	<0.0001
3 (a = c)	1.764 (1)	0.184
0 (no restrictions)	0 (0)	1.00