| Abstract: | This paper explores the possibility of using different techniques of time-series analysis lagged regression analysis for the study of the complicated interaction between ecological, socioeconomic and nutritional variables. The data discussed originate from a rural area in Tanzania, where life is subject to a marked seasonal variation, dependent on a bi-modal rainfall pattern. The unreliability of rainfall is characteristic: both drought and excessive rainfall are frequent occurrences. Seasonal variationns in birthweights over a 10-year period (1972-81) are here compared with the local rainfall pattern. Data on birthweight for this period show that birthweight was highest at the end of the dry season, fell rapidly during the 1st 1/2 of the rainy season, rose again during the later part of the rainy season, and fell to its lowest value just after the rans. It is argued that there are good reasons to attribute these variations to changes in labor output, food consumption, and health status, all of which are related to the seasonal cycle. Mean birthweight fell by about 60g. in the course of the rainy season. Lagged regression analysis reveals a negative impact of rainfall on birthweight after 3 months. Deviations from average rainfall show a positive correlation with birthweight after 4 months, but only in the months when rainfall is critical for food crop production. The interactions of these contrary effects are held responsible for the observed sudden fluctuations in mean birthweight. |
