Table 2.

Model Parameterization Comparisons

	Approach 1 Varying Variance	Approach 2 Invariant Variance	Approach 3 No Variance
Group 1: Escalators
Intercept µ	1.36 (.10)	1.22 (.15)	1.31 (.11)
Intercept σ	.19 (.03)	.12 (.02) =	0.00
Slope µ	.30 (.05)	.55 (.07)	.29 (.04)
Slope σ	.002 (.000)	.001(.00)=	0.00
Quadratic µ	−.021 (.004)	−.042 (.005)	−.021 (.002)
Class Proportion	24.4%	9.3%	17.6%
Group 2: Decliners
Intercept µ	3.67 (.21)	3.85 (.17)	3.97 (.19)
Intercept σ	.19 (.03)	.12 (.02) =	0.00
Slope µ	−.32 (.05)	−.31 (.05)	−.23 (.07)
Slope σ	.002 (.000)	.001 (.00)=	0.00
Quadratic µ	.013 (.003)	.012 (.003)	.003 (.005)
Class Proportion	11.1%	10.0%	6.9%
Group 3: Low Null Growth
Intercept µ	1.32 (.05)	1.36 (.04)	1.22 (.02)
Intercept σ	.08 (.03)	.12 (.02) =	0.00
Slope µ	.04 (.009)	.06 (.01)	.05 (.01)
Slope σ	.000 (.000)	.001(.00)=	0.00
Quadratic µ	−.004 (.001)	−.005 (.001)	−.004 (.001)
Class Proportion	64.5%	80.7%	57.2%
Group 4: High Escalator
Intercept µ			1.87 (.25)
Intercept σ			0.00
Slope µ			.47 (.09)
Slope σ	NA	NA	0.00
Quadratic µ			−.035 (.007)
Class Proportion			5.4%
Group 5: Low Decliner
Intercept µ			2.47 (.17)
Intercept σ			0.00
Slope µ			−.10 (.06)
Slope σ	NA	NA	0.00
Quadratic µ			0.00(.004)
Class Proportion			13.0%

⁰Fixed to zero

⁼Fixed to be equal across class