Table 2. Four-Group Latent Growth Model of Composite Memory Performance: Results from ACTIVE (n = 629).
| Initial training | Booster training | |||||||
|---|---|---|---|---|---|---|---|---|
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| Non-adherent A | Adherent A | Non-adherent B | Adherent B | |||||
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| β (SE) | Effect size | β (SE) | Effect size | β (SE) | Effect size | β (SE) | Effect size | |
| Means | ||||||||
| Intercept | -0.51 (0.29) | (REF) | 0.07 (0.16) | 2.86 | -0.49 (0.21)* | 0.08 | 0.61 (0.14)* | 5.77 |
| Slope (normal aging) | -0.16 (0.06)* | (REF) | -0.20 (0.03)* | 1.00 | -0.13 (0.05)* | 0.55 | -0.17 (0.03)* | 0.25 |
| Training effect | -0.06 (0.21) | (REF) | 0.54 (0.09)* | 4.52 | 0.53 (0.11)* | 3.79 | 0.54 (0.09)* | 4.45 |
| Variances | ||||||||
| Intercept | 4.57 (0.93)* | 4.64 (0.40)* | 5.20 (0.49)* | 3.58 (0.36)* | ||||
| Slope (normal aging) | 0.02 (0.03) | 0.02 (0.01) | 0.06 (0.03)* | 0.04 (0.01)* | ||||
| Training effect | @0 | 0.28 (0.20) | 0.82 (0.30)* | 0.33 (0.18) | ||||
| Covariance(Intercept, Slope) | 0.10 (0.14) | 0.08 (0.06) | -0.04 (0.08) | 0.09 (0.04)* | ||||
| Model fit statistics | ||||||||
| Model χ2 (df) | 85.93 (57), p=0.01 | |||||||
| Contribution to χ2 | 14.76 | 15.86 | 37.55 | 17.77 | ||||
| CFI | 0.988 | |||||||
| RMSEA | 0.057 | |||||||
| SRMR | 0.047 | |||||||
Note. Results from a four-group latent growth curve model of equipercentile-equated composite memory performance for each adherence group. The model setup is displayed graphically in Figure 1. Means of latent variable intercepts and slopes are free to vary by adherence group. Asterisks indicate parameter estimates are significantly different from zero (p < 0.05). Effect sizes represent Cohen's d effect sizes for group differences in a parameter relative to the Non-adherent-A group.
0 indicates the variance of the training effect in the Non-adherent A group was fixed at 0 for model convergence. Residual variances of observed dependent variables were freely estimated, results of which are not shown. SE: standard error; CFI: Comparative fit index; RMSEA: Root mean square error of approximation; SRMR: Standardized root mean square residual. Mean intercept values differed significantly (p < 0.05) by group: Non-adherent A < Adherent A = Non-adherent B < Adherent B. Mean slopes did not differ across group. For the training effect, Non-adherent A < Adherent A = Non-adherent B = Adherent B.