F) EL SER SOCIAL Y LAS CATEGORÍAS ECONÓMICAS

different cut-off points in various studies has just been published (Bohning et al., 1992). The method, termed ABC (area between curves) method, could not be used in this study because the analysis was completed before the publication was available.

Fig 5.1: Comparison of observed SD-scores for height-for-age and weight-for-height among Ondo State children with NCHS/WHO

reference

SD-Scores

H e ig h t- fo r - A g e ---W eight-for-Height...International Reference

of ODHS children towards the negative side of the scale, they could be characterized as mildly undernourished. Hence, the presentation of the data in this study will be in standard deviation from the reference median.

In the present analysis, the reference used (NCHS/WHO) has been recommended as meeting all set criteria for international comparison of anthropometric measurements by the WHO expert group (WHO, 1983:61). The formula for calculating standard deviation score (referred to in this chapter as SD-score or Z-score) is given by WHO (1983:24) as

(Individual's value) - (median value of reference population) Standard deviation of reference population

The median is used for the calculation of the standard deviation score because in the continuum of Z-scores from -x to +x, zero is the midpoint or the 50th centile. In a normal distribution (Gaussian) curve, the mean and the median are approximately the same. The anthropometric data for the NCHS reference population had been normalized by the Center for Disease Control (CDC) and these normalized growth curves have been used worldwide since 1978 both to monitor the growth of children and to assess the nutritional status of populations of children from surveys (Dibley, Goldsby et al., 1987:737). The above formula gives a comparison of where an individual's anthropometric value falls relative to the reference population. If a child's standard deviation score for either weight-for-age, height-for-age or weight-for-height is less than, or equal to, -3.00, the child is considered severely underweight, severely stunted or severely wasted. A child with a standard deviation score between -2.99 and -2.00 is considered moderately stunted or wasted (Graitcer et al., 1981:293). A standard deviation score that falls between -1.99 and -1.00 indicates mild undemutrition. Above the -1.00 SD-score, the child is considered normal.

Age grouping

The accuracy and interpretation of height-for-age as an index of nutrition depend, to a large extent, on the recorded age of the child (Binns, 1985:123). Causes of growth failure in children are age-specific (Beaton et al., 1990:5). Ideally in the measurement of age-related anthropometric indicators, age should be obtained through birth registration or clinical records. Unfortunately, in many parts of the Third World, births are not registered and where birth registration exists, the coverage is poor.

For example, in a situation where age data are not routinely collected and birth certificates are not available, WHO (1983:19) suggests that age-related anthropometric data be presented in months as follows: 0-5, 6-11, 12-23, 24-47, 48-71, 72-95, 96-119. In the ODHS, anthropometric data were not collected on children aged 0-5 months and those aged above 36 months. Ages in this analysis are classified in six-month intervals to allow for a closer observation of various patterns in the child's nutritional status as it grows older. This is a slight variation of the recommendation by Waterlow et al. (1977:491). Vahlquist (1979:154) refers to children aged 6-11 months as older infants whose food consists of human milk with a gradual addition of solid and semi-solid supplementary foods. Between the ages of 12 months and 36 months, most children are weaned and weaning foods are available to the child according to local conditions, socio-economic status and culture. The mean duration of breastfeeding in Ondo State was 18 months in the ODHS data (Ministry of Health, 1989:17).

The focus of analysis in this chapter is on children between ages six months and 36 months who were measured between September 1986 and January 1987 during the 1986-1987 Ondo State Demographic and Health Survey (ODHS). As part of the survey, data on weight and recumbent length (henceforth referred to as height) of children between age six months and 36 months were collected. Originally, the data file was part of the women's file; to make analysis easier, a child-file was created as a subset of the mother file. The child file contained about 1600 children, and is the primary source of the data for this chapter. Some citations from a recent micro-level qualitative

study (EAMS1 and EAMS2) are included to add socio-economic and cultural context to the observed pattern in the survey data.

Anthropometric measurements in their raw (uncoded) forms are continuous numbers. They, as well as the individual Z-scores are therefore, amenable to regression methods and multiple classification analysis. In the analysis that follows, means and variances of the height-for-age and weight-for-height data are calculated using the one-way analysis of variance method of the Statistical Package for Social Sciences (SPSS-X). The significance of the F-statistics for between-group differences in the analysis of variance of the observed means are presented while those for within-group and test of linearity, which are not essential for the purpose of this thesis, are not reported. A multivariate analysis using multiple regression techniques is also presented below.

RESULTS AND DISCUSSION