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Table 3 Absolute values of relative bias of intercept (int) and slope per analysis model: findings over 1000 replications in the simulation for a sample size of 300 and 100 and low degree of separation between classes in Scenario 1

From: Variance constraints strongly influenced model performance in growth mixture modeling: a simulation and empirical study

Model   Intercept class 1 Intercept class 2 Intercept class 3 Slope class 1 Slope class 2 Slope class 3
Low separation and N = 300
 0 Nothing constrained .00 .01 .00 .00 .03 .01
 1A Residual variance time constrained .00 .01 .00 .00 .10 .08
 1B Residual variance classes constrained .01 .03 .00 .00 .10 .00
 1C Random effects constrained .01 .01 .02 .01 .00 .04
 2A Residual variance constrained time and classes .01 .04 .00 .00 .22 .03
 2B Random effects and residual variance time constrained .01 .02 .01 .01 .03 .20
 2C Random effects and residual variance classes constrained .13 .29 .03 .08 1.23 .37
Low separation and N = 100
 0 Nothing constrained .01 .05 .01 .01 .04 .18
 1A Residual variance time constrained .01 .02 .01 .01 .08 0
 1B Residual variance classes constrained .01 .05 .01 0 .07 .18
 1C Random effects constrained .02 .02 .02 .01 .06 .07
 2A Residual variance constrained time and classes .02 .07 .01 .02 .37 .02
 2B Random effects and residual variance time constrained .01 .03 .01 .01 .08 .26
 2C Random effects and residual variance classes constrained .13 .19 .01 .03 1.06 .47
  1. Relative bias: bias divided by true population value
  2. Codes for relative bias: Bold ≥ .1
  3. The variance ratio in Scenario 1 is 1:3 across classes and over time points, which means that the variance in the first class/time-point is three times smaller compared to the last class/time-point
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BMC Medical Research Methodology

ISSN: 1471-2288

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