|Chronic Energy Deficiency : Consequences and Related Issues (International Dietary Energy Consultative Group - IDECG, 1987, 201 pages)|
|Methodology of field studies related to socioeconomic effects of chronic energy deficiency|
|4. Human capital studies|
Certain methodological aspects of human capital studies have been summarized in Table 1. These studies in the past have mainly employed a cross-sectional design, using as the experimental variable the variation in nutritional status encountered in the study subjects. Body composition indicators or daily energy intakes have been used to represent levels of chronic energy deficiency.
The few relevant studies which are available have used economically active adults as subjects within a homogeneous occupational group. In one case, a parameter of childhood nutrition (adult stature) was associated with adult productivity in order to quantify human capital formation via nutritional investment during childhood (IMMINK et al., 1984). In another study, it was demonstrated that in a cohort of children protein-energy intake levels were related to their mental development. In a cohort of adult workers from the same social stratum as the cohort of children, mental development was related to productivity (SELOWSKY and TAYLOR, 1973). The general conclusion of the study was that undernutrition in children represents disinvestment in human capital.
Alternative key economic indicators which can be used for the analysis are (a) total income from all productive activities, including the imputed market value of home production activities; (b) total earnings, in wage employment, or (c) number of work units performed and valued at market wage rates. The first indicator is preferable though costly in terms of data requirements. Direct questions regarding income earned usually result in a systematic under-reporting1.
1 This may not be serious it the reporting
bias is a constant proportion of true income, but this is usually not the
Alternatively, as a proxy of earned income, total expenditures (plus net changes in savings if relevant) are often used.
Longitudinal studies which involve an induced change in nutritional status, either by means of supplementation or naturally occurring change in energy availability, offer an opportunity to undertake internal rate-of-return analysis, assuming that the measurement period is sufficiently long to measure the full impact on productivity. Relevant supplementation studies (see section 3) did not demonstrate any significant productivity effect during the measurement periods. To the author's knowledge no human capital analysis has been applied in longitudinal CED studies.