An Analysis of Yam consumption Patterns in Ghanaian Urban Communities

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This study examined the major factors that drive changes in yam consumption patterns across income groups, seasons and urban centers in Ghana to inform food policy formulation. The study, among other things, sought to provide evidence on whether or not yam had become a luxury food commodity in Ghanaian urban communities. Special attention was also given to the question of whether household income allocation between males and females had any significant effect on yam consumption. Quarterly household panel data collected from four urban centers were used to conduct a complete demand system analysis by employing the Almost Ideal Demand system (AIDS) and Quadratic Almost Ideal Demand System (QUAIDS) models through the use of the Ordinary Least Squares (OLS) method. The study estimated yam expenditure elasticities for the pooled/aggregate data and the four different urban centers across different income groups to test Engel’s law. Results of the study showed that majority (>80%) of yam consumers in Ghanaian urban communities preferred white yam to yellow and water yams, and the most important reason for their preference was taste. Boiled yam (ampesi) was the most preferred yam product in Ghanaian urban centers followed by pounded yam (fufu). Rice was identified as the most important substitute for yam in urban communities. In a typical Ghanaian urban center, household food budget formed about 51% of the total household budget. Yam constituted about 12% of household at-home food budget and 13% of its away-from-home food budget. The shares of food budget that households allocated to yam generally increased during the peak harvest season and dropped during lean season across all urban centers in Ghana. Yam expenditure elasticity for the pooled sample was found to be inelastic (0.76), suggesting that yam is a basic food commodity in a typical Ghanaian urban center. Yam expenditure elasticity was lowest for Tamale (0.64), a less urbanized center, and highest for Accra (1.01), a more urbanized center. Generally, across urban centers, the study supported Bennett’s law which posits that households switch from less to more expensive calorie consumption as their incomes increase. However, in each particular urban center, Engel’s law was affirmed; yam expenditure elasticity was higher for low-income households and lower for high-income households. Yam expenditure elasticity was found to vary across seasons; yam was expenditure elastic during the lean season and expenditure inelastic during the harvest season. Women’s share of household income was found to be positively related to household yam budget share. Evidence from this study did not support the hypothesis of economies of household size with respect to household yam budget share when the pooled data was used for analysis. However, the hypothesis of economies of household size was supported in the seasonal consumption analysis where households were found to enjoy economies of size during the relatively yam abundant period of August to December and diseconomies of size during the lean season. The study showed that yam budget share was own-price elastic but expenditure inelastic. Urban households were more responsive to changes in yam prices than changes in household income, implying that the substitution effect is stronger than the income effect. The high price elasticity for yam budget share stresses the importance of food price changes for households, and it is important that households’ reactions are taken into account in the development of comprehensive agricultural and food policies in Ghana. Based on the findings of the study, recommendations have been made to help improve the Ghanaian yam sector and household food security in urban centers.
A dissertation submitted to the School of Graduate Studies, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana in Fulfillment of the Requirements for the degree of Doctor of Philosophy.