Table 6. Results of linear regression models predicting children’s vocabulary growth.

Family wise alpha = .05.

	Model Parameter	B	SE	T	df	p
Using average rates as language input predictors	Child vocalizations	-1.92	.65	-2.96	12	.025
	Adult vocalizations	-1.15	.33	-3.51	12	.013
	Peer vocalizations	1.10	.32	3.41	12	.014
	Turn-taking	3.87	1.21	3.21	12	.018
	Sex	.44	.31	1.42	12	.205
	Age	-.003	.001	-2.21	12	.069
Using change over time as language input predictors	Child vocalizations	-.003	.001	-2.58	12	.042
	Adult vocalizations	-.002	.08	-2.87	12	.028
	Peer vocalizations	.002	.07	3.34	12	.016
	Turn-taking	.007	.003	2.76	12	.033
	Sex	.53	.33	1.61	12	.159
	Age	-.003	.001	-1.89	12	.108