Table 5. Results of separate linear mixed effects regression models predicting changes in children’s daily vocalizations over time.
Family wise alpha = .0125.
| Fixed effects | Random effects | Chi-square test of model fit with and without effect | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Model Outcome | Model Parameter | B | SE | t | X2 | Df | p | ||
| Adult vocalizations | Time | .002 | .002 | 1.23 | — | — | 1.55 | 1 | .213 |
| Child vocalizations | -1.04 | .16 | -6.59 | — | — | 39.85 | 1 | < .00001 | |
| Peer vocalizations | .83 | .09 | 9.32 | — | — | 71.87 | 1 | < .00001 | |
| Turn-taking | 2.50 | .21 | 11.99 | — | — | 106.16 | 1 | < .00001 | |
| Sex | .26 | .37 | .71 | — | — | .53 | 1 | .468 | |
| Subject intercept | — | — | — | 0 | 0 | 0 | 1 | 1 | |
| Turn-taking | Time | .0004 | .0005 | .93 | — | — | .76 | 1 | .384 |
| Child vocalizations | .50 | .03 | 17.26 | — | — | 160.97 | 1 | < .00001 | |
| Adult vocalizations | .19 | .02 | 11.91 | — | — | 103.75 | 1 | < .00001 | |
| Peer vocalizations | -.20 | .03 | -7.52 | — | — | 50.29 | 1 | < .00001 | |
| Sex | -.26 | .10 | -2.43 | — | — | 6.12 | 1 | .013 | |
| Subject intercept | — | — | — | .003 | .05 | 0 | 1 | 1 | |
| Child vocalizations | Time | -.001 | .008 | -1.30 | — | — | 1.66 | 1 | .20 |
| Adult vocalizations | -.19 | .03 | -6.04 | — | — | 34.05 | 1 | < .00001 | |
| Peer vocalizations | .34 | .04 | 8.45 | — | — | 61.38 | 1 | < .00001 | |
| Turn-taking | 1.24 | .08 | 16.01 | — | — | 154.72 | 1 | < .00001 | |
| Sex | .10 | .23 | .45 | — | — | .23 | 1 | .632 | |
| Subject intercept | — | — | — | .71 | .84 | 2.81 | 1 | .094 | |
| Peer vocalizations | Time | .004 | .001 | 3.61 | — | — | 11.13 | 1 | .0008 |
| Child vocalizations | .91 | .11 | 8.49 | — | — | 62.11 | 1 | < .00001 | |
| Adult vocalizations | .41 | .05 | 9.08 | — | — | 68.78 | 1 | < .00001 | |
| Turn-taking | -1.31 | .18 | -7.40 | — | — | 49.21 | 1 | < .00001 | |
| Sex | .03 | .33 | .08 | — | — | .003 | 1 | .955 | |
| Subject intercept | — | — | — | .11 | .33 | .04 | 1 | .852 | |