Table 3.

Summary of spline logistic regression for singing by country

Country	M	SD	Knot estimate	rpb (0–4mo)	rpb (5–11mo)
High HDI	.81	.39	3.259	.12***	.04
Albania	.82	.39	−1.172	.04	.06
Belarus	.84	.36	17.083	.13	.14**
Bosnia and Herzegovina	.67	.47	5.001	.06	.06
Kazakhstan	.88	.32	4.394	.13*	.08
Macedonia	.75	.43	5.503	.16*	−.03
Montenegro	.96	.20	2.361	.39**	.09
Serbia	.76	.42	3.675	.21***	.00
Trinidad and Tobago	.91	.29	−4.534	−.03	.05
Medium HDI	.54	.50	1.461	.16***	.04***
Bangladesh	.37	.48	1.554	.18***	.07***
Belize	.77	.42	1.000	.22	.19
Cameroon	.62	.49	7.000	.15***	.07
Djibouti	.12	.33	−1.419	.03	−.00
Georgia	.74	.44	1.529	.19*	.01
Ghana	.68	.46	2.000	.15**	.07
Guyana	.78	.42	4.261	.23***	−.02
Jamaica	.82	.38	3.147	.21*	.09
Kyrgyzstan	.66	.47	1.460	.20***	−.00
Laos	.10	.30	6.000	.08	−.01
Mauritania	.51	.50	6.302	.29***	.09**
Mongolia	.50	.50	7.000	.07	.06
Suriname	.79	.41	6.551	.18*	−.00
Syria	.64	.48	7.001	.12***	.02
Tajikistan	.66	.47	4.996	.04	.04
Thailand	.78	.41	4.807	.17***	.01
Uzbekistan	.78	.41	7.000	.10	.07
Vanuatu	.78	.41	4.695	.19***	−.02
Vietnam	.30	.46	8.000	.15*	.20***
Yemen	.39	.49	3.000	.19***	.05
Low HDI	.54	.50	3.623	.14***	.03***
Burkina Faso	.18	.38	5.564	.09	.01
Central African Republic	.66	.47	2.413	.18***	.02
Côte d’ Ivorie	.55	.50	4.701	.11**	.01
Gambia	.30	.46	4.360	.15***	.08*
Guinea-Bissau	.53	.50	1.062	.15***	.06
Nigeria	.65	.48	3.374	.22***	.05*
Sierra Leone	.77	.42	7.949	.13**	.06
Togo	.75	.43	2.000	.14**	.07
HDI N/A	.49	.50	4.304	.15***	−.02
Iraq	.42	.49	6.035	.14***	.01
Somalia	.68	.47	1.494	.15***	.05
TOTAL	.56	.50	4.329 a	.15***	.03***

Note. HDI = Human Development Index. Correlations that significantly changed at 4 months of age are bolded.

^*p ≤ .05.

^**p ≤ .01.

^***p ≤ .001.

^aAverage of individual country knots excluding out-of-range estimates.