Descriptive statistics
Table 2 reveals percentile of HAZ scores adjusted by kernel smoothing for the four rounds of NFHS. HAZ scores of first and second rounds of NFHS are not strictly comparable because of territorial changes as mentioned earlier. The HAZ values of Bihar were also compared with the HAZ values of overall India. Without loss of generality, one can note that absolute increase in overall HAZ scores was the highest between second and third rounds of NFHS (i.e. between 1998-99 and 2005-06) followed by third and fourth rounds i.e. between 2005-06 and 2015-16. Child’s HAZ scores largely remained at the same level between 1992-93 and 1998-99. Absolute increase of child’s HAZ scores was remarkable for the bottom quantiles between 1998-99 and 2005-06 nationally and in Bihar, in particular. In Bihar, there was even decline of HAZ scores at the top quantile. However, between 2005-06 and 2015-16, absolute increase in the HAZ scores was observed at the top quantile nationally as well as in Bihar. In other words, nutritionally better-off children gained more compared to the severely stunted during last decade.
--< Table 2: Percentile of HAZ score in NFHS 1, NFHS 2, NFHS 3 and NFHS 4 in Bihar and India>--
Table 3 depicts socio-demographic and economic characteristics of the samples in four rounds of NFHS. It has been observed that initiation of early breastfeeding (within one hour of birth) has improved dramatically – more than 14-times – between 2005-06 and 2015-16. Although number of siblings of the index child has been declined in the recent past, it still indicates fertility in the state is high. Notably, benefit received from ICDS services increased by more than 7-fold between 2005-06 and 2015-16. Similar is the case for institutional delivery of mothers. Mother’s age at first child has increased by nearly two years during the study period. BMI of mothers has improved between 2005-06 and 2015-16, while rate of decline of anaemia was substantial between 1998-99 and 2005-06 compared to 2005-06 and 2015-16. Mother’s educational level has improved marginally in all the rounds. Although workforce participation rate among mothers remained consistent around 20 percent during 1992-93 and 2005-06, it has declined by half between 2005-06 and 2015-16. Degree of media exposure was found to have increased marginally over the years.
Majority of the respondents in the sample was Hindu and non-SC/ST, including OBCs. It is surprising to find out that proportion of economically marginalized households in the sample has increased from 1998-99, in spite of the state’s higher economic growth during these periods, particularly after 2005 [36]. Being the least urbanised state of the country (among the major states), overwhelming proportion of the sample belong to the rural areas of Bihar.
--< Table 3: Sample Characteristics of Child age 0-35 months according to Background Characteristics in Bihar >--
Unconditional RIF quantile regression results
The estimates derived from unconditional RIF quantile regressions (QR) separately for all the survey periods were shown in Tables 4 and 5. It has been observed that child age has negative and significant influence with child’s HAZ scores across quantiles. If one moves from the lower tail to the upper tail, this effect increases, indicating that children starting with better nutritional status stand to lose more through faltering as they grow older. Although such observation holds for second and third rounds of survey, said observation confirms up to 75 percent quantile for first and fourth rounds. Girls were found to have significantly better HAZ outcomes compared to boys across quantiles; however, strength of association varies across quantile and period of survey. Child’s size at birth (proxy for birth weight) was found to have varying association with HAZ scores across quintiles during first two rounds, in third and fourth rounds, size of the birth of children did not have any significant effect on HAZ scores. Early initiation of breastfeeding found to have positive and significant effect on HAZ scores in first round, while such effect weakened during the last three rounds. Higher sibling size has negative significant influence on child’s HAZ scores, particularly those belong to the lower quantiles in third and fourth rounds of survey. Receipt of any benefit from ICDS found to be negatively associated with child’s HAZ scores and such effect increases when we go from lower tail to higher tail of the HAZ distribution in the last round of survey.
Institutional delivery of mother, which is an important indicator for contact with health personnel, has positive and significant influence on child’s HAZ scores across quantiles, particularly at the lower and middle quantile in varying degree except during the third round of the survey. Significant positive effect of higher age of mother’s first birth on child’s HAZ outcomes was found in the higher quantiles during the first and the latest rounds of survey, but not in other rounds. Notably, significant positive influence of maternal education on child’s HAZ scores decreased with rounds.
---< Table 4: Unconditional Re-centred Influence Function (RIF) Quantile Regression Results for NFHS 1 (1992-93) and NFHS 2 (1998-99) in Bihar >---
---< Table 5: Unconditional Re-centred Influence Function (RIF) Quantile Regression Results for NFHS 3 (2005-06) and NFHS 4 (2015-16) in Bihar >---
Working mothers are significantly more likely to have children with lower HAZ scores compared to their non-working counterparts across quantiles during first round of the survey; however, such association holds only in lower quantiles in second and fourth rounds. Mother’s exposure to any mass media found to have positive significant influence in the middle and upper quantiles of HAZ scores in the first round, though weakened in other rounds. Maternal height and BMI both have small but significant influence in enhancing child’s HAZ scores across quantiles, such association strengthen in the last two rounds of survey. Degree of maternal empowerment found to have positive significant effect on child’s HAZ scores during second round of the survey; however, such relationship weakened during last two rounds.
Differentials with respect to religion and caste affiliation were found in child’s HAZ scores during first round of the survey; however, the relationship weakened thereafter. Significant positive influence of household affluence on child’s HAZ outcomes was found during first and third round of survey and observation suggests the effect is higher among those belonging to higher quantiles. The results also revealed that rural-urban differentials in child’s HAZ outcomes diminished over the period in Bihar.
Quartile regression Oaxaca Blinder counterfactual decomposition (QR-CD)
The estimated QR-CD results at the aggregate level of child, maternal, household and spatial characteristics were presented in the Tables 6-8, while a detailed breakdown of contribution of these characteristics were given in the Appendix Tables A1-A3.
Before interpreting the results, it should be kept in mind that the negative sign of the observed raw gap in HAZ scores between two successive periods reflects the fact that raw HAZ scores of the later period was lower than the previous period in all quantiles, except at the highest quantile between second and third rounds. Additionally, it must also be kept in mind that the direction of effect of contribution of characteristics as shown in the Tables 6-8 – negative figures imply a contribution to increase in the disparity in HAZ scores over time, while positive figures show a contribution to diminish it. A careful look to these tables reveals certain pattern of covariate effects and coefficient effects across quantiles and over the periods.
---< Table 6: Oaxaca Blinder Decomposition of HAZ Scores of NFHS 1 and NFHS 2 in Bihar >---
---< Table 7: Oaxaca Blinder Decomposition of HAZ Scores of NFHS 2 and NFHS 3 in Bihar >---
---< Table 8: Oaxaca Blinder Decomposition of HAZ Scores of NFHS 3 and NFHS 4 in Bihar >---
It may be observed that between the periods 1992-93 and 1998-99 covariate (or endowments) effects contributed significantly to enhance disparities in child HAZ outcomes, at the 10th, 50th and 75th quantiles, while coefficient (returns to endowments) effects dominates over covariate effect in enhancing disparities in child’s HAZ outcomes at 90th quantile (see Table 6). Lower panel of the Table 6 suggests that child endowments alone contributed 36.5 percent at 90th quantile to 270.8 percent at 25th quantile in explaining disparities in child’s HAZ outcomes. Effect of mother’s characteristics (or mother’s endowments) in explaining such disparities was found to be relatively small and varies between -8.8 percent at 90th quantile to 38.4 percent at 25th quantile, while effects of household characteristics have tried to reduce covariate effects, particularly in 10th and 25th quantiles.
Notwithstanding, the directions of covariate and coefficient effects reversed significantly between the periods 1998-99 and 2005-06 as well as between 2005-06 and 2015-16 (see Tables 7 and 8). During both the periods, coefficient effects (or returns to endowments) significantly surpassed covariate effects (or endowments) in most of quantiles except the bottom quantile. Between 1998-99 and 2005-06, coefficient effects enhanced disparities in child’s HAZ outcomes by 89 – 254.5 percent between 25th and 75th quantiles (see Table 7), while such effects vary between 117 – 168.7 percent between the same quantile (see Table 8). Additionally, between the said periods, coefficient effects enhanced disparity in child’s HAZ outcomes even at the 90th quantile. The lower panels of the Tables 7 and 8 revealed that between 1998-99 and 2005-06, coefficient effects of child characteristics significantly increased disparities across quantiles, while said effects of mother’s characteristics have tried to reduce it except at 25th and 50th quantiles. Further, coefficient effects of the household attributes have tried to increase disparities in HAZ outcomes significantly at 25th and 75th quantiles between 1998-99 and 2005-06 and 10th to 50th quantiles between 2005-06 and 2015-16. Additionally, during the last period, positive and significant covariate effects were observed at the higher tails of HAZ distribution.
If covariate effects and coefficient effects of different attributes are looked in more disaggregated manner during the study period (as given in the Appendix A1-A3), it has been found that these effects vary across quantiles, periods and nature of endowment. For example, delivery in institutions was found to have significant effect in enhancing disparities, particularly between lower tails of the HAZ distribution between 1992-93 and 1998-99 (Appendix Table A1), coefficient effects of mother’s height and BMI, and, media exposure have tried to reduce disparities across quantiles between 1998-99 and 2005-06 (Appendix Table A2). During the same period, covariate effect of institutional delivery has contributed significantly in increasing disparities. Between 2005-06 and 2015-16, both covariate and coefficient effects of the receipt of ICDS services were found to be significantly associated with reduction of HAZ disparities among children (Appendix Table A3).