Equity of access to maternal health interventions in Brazil and Colombia: a retrospective study

Table 3 Concentration indices and key statistics

Interventions	Brazil							Colombia
Interventions	C	Mean coverage rates (μ)	C normalized = (C/1 - μ)	SE (C)	t (C)	Low	High	C	Mean coverage rates (μ)	C normalized = (C/1 - μ)	SE (C)	t (C)	Low	High
ANC (4 visits or more)	0.022	0.91	0.506	0.013	1.70	-0.004	0.048	0.024	0.93	0.329	0.008	3.13	0.008	0.039
SBA	0.032	0.93	0.836	0.013	2.37	0.005	0.059	0.035	0.94	0.612	0.015	2.36	0.005	0.065
C-section	0.207	0.39	0.362	0.055	3.74	0.095	0.318	0.097	0.35	0.150	0.029	3.30	0.038	0.157
PNC (within 2 months after birth)	0.277	0.32	0.456	0.068	4.05	0.14	0.415	0.123	0.27	0.168	0.028	4.32	0.066	0.180

SE standard errors, t (C) = t-values and Low and High are the 95% confidence intervals limits
The t variable for C is defined as t = C/SE(C)
The critical value t_α/2 of the variable t for the confidence intervals is obtained from the t distribution for α/2 (2, 5%) level of significance and 38–40 df (degrees of freedom)
The 95% confidence interval for C is given by: C ± t_α/2 SE (C)
SBA skilled birth assistance, PNC postnatal care

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