Table 4. Results of linear mixed effects regression models predicting children’s daily vocalizations rates.
| Fixed effects | Random effects | Chi-square test of model fit with and without effect | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Model Parameter | B | SE | t | Variance | SD | X2 | df | p | |
| Including turn-taking as a covariate | Adult vocalizations | -.19 | .03 | -6.18 | — | — | 35.31 | 1 | < .00001 |
| Peer vocalizations | .33 | .04 | 8.12 | — | — | 56.95 | 1 | < .00001 | |
| Turn-taking | 1.24 | .08 | 15.84 | — | — | 153.20 | 1 | < .00001 | |
| Sex | .10 | .23 | .42 | — | — | .23 | 1 | .628 | |
| Age | -.00009 | .0006 | -.14 | — | — | .03 | 1 | .863 | |
| Subject intercept | — | — | — | .08 | .28 | 1.37 | 1 | .24 | |
| Not including turn-taking as a covariate | Adult vocalizations | .10 | .04 | 2.64 | — | — | 6.99 | 1 | .008 |
| Peer vocalizations | .25 | .06 | 4.00 | — | — | 15.13 | 1 | .0001 | |
| Sex | -.54 | .52 | -1.11 | — | — | 1.41 | 1 | .235 | |
| Age | -.0001 | .001 | .09 | — | — | .02 | 1 | .882 | |
| Subject intercept | — | — | — | .59 | .77 | 24.83 | 1 | < .00001 | |
Note. Adult vocalizations, peer vocalizations, and turn-taking all predict children’s daily vocalization rates. When turn-taking with adults is removed as a predictor, the negative association between adult vocalizing and child vocalizing becomes a positive association. Family wise alpha = .05.