Demand analysis for selected roots and tubers among urban households of Nakuru County, Kenya

Abstract

This study examines Kenya’s demand for selected roots and tubers (R&Ts). Data used for the analysis were collected from Nakuru Town East Sub-County. A sample unit of 385 urban households was interviewed at the market outlet immediately after purchasing R&Ts. Linear Approximated Almost Ideal Demand System (LA/AIDS) model was used to estimate demand elasticities, demographics and social-economic factors influencing the consumption patterns of R&Ts. Age, education, household size, and proportion of household members statistically and significantly explained the variations in R&Ts consumption patterns. Empirical results showed negative own-price elasticities for uncompensated and compensated demand analyses, therefore in line with utility theory. Cross-price elasticities had positive and negative signs, indicating the presence of substitutes and complements respectively among R&Ts. Expenditure (income) elasticities for R&Ts had mixed signs ranging from elastic to inelastic. Irish potato and sweet potato were inelastic with a positive sign classifying them as necessities goods. Cassava and yam were inelastic with a negative sign indicating they were inferior goods, while arrowroot was positive and elastic, therefore a luxury good. These results are broadly consistent with microeconomic theory; consequently, they could inform the formulation of effective policies and strategies that promote R&Ts consumption thereby contributing to food and nutritional security among households.

Keywords:

• Budget shares
• consumer demand
• household consumption
• linear approximated almost ideal demand system
• root and tuber crops

PUBLIC INTEREST STATEMENT

Roots and tubers (R&Ts) are affordable and cheap sources of carbohydrates, vitamins A, B, and C, and essential elements; iron, zinc, and calcium, and serve as staple foods worldwide. In this paper, we show the factors influencing demand for R&Ts among urban consumers who are most vulnerable. This is significant because it seeks to encourage their consumption, especially by the urban poor. We also believe that the findings presented in this paper will appeal to the general public to enhance R&Ts demand. The estimates in this paper add to the growing literature on root and tuber demand using the LA-AIDS framework. LA-AIDS model showed that the own-price elasticities of the selected five root and tubers are valued to be negative, meaning that every price increase will reduce the demand. Moreover, cross-price elasticities are a mixture of positive and negative values, implying the R&Ts are a mixture of substitutes and compliments.

Acknowledgements

The authors are very thankful for the financial support offered to the first author by the African Economic Research Consortium (AERC). The funding made the research study a success. In a big way, we would also thank and appreciate the positive cooperation received from the enumerators during the data collection exercise. We also recognise the cooperation of the interviewed consumers during the survey.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author (FON) upon reasonable request.

Notes

1. Bashara, Flamingo, Kivumbini, Menengai, and Nakuru East wards.

2. Decision-maker is the household member responsible for making food consumption decisions.

3. Real monthly expenditure refers to the index scaled expenditures (Stones price index).

4. KES refers to Kenyan shilling (official Kenyan currency); exchange rate is 1 $US = KES. 113.05.

5. Normal foods are food groups whose demand increases with an increase in income.

6. A luxury food is a normal food whose income elasticity of demand is greater than one.

7. Necessity foods are normal foods whose income elasticity of demand lies between zero and one.

8. Inferior foods are foods whose demand drops with an increase in consumer’s income.

Additional information

Funding

This work was supported by the African Economic Research Consortium (AERC) under thegrant [AE/TG/19-02 (Award 1310)].

Notes on contributors

Fredrick O. Nuani

Mr. Fredrick Ouma Nuani is an African Economic Research Consortium (AERC) scholar pursuing a Collaborative Master of Science degree in Agricultural and Applied Economics at Egerton University, Kenya and University of Pretoria, South Africa. Dr. Eric Obedy Gido has a PhD in Agricultural Economics and currently serves as a lecturer in the Department of Agricultural Economics and Agribusiness Management, Egerton University. His main area of interest is on consumer studies and has taught several courses over the years. Dr. Oscar Ingasia Ayuya is a senior lecturer in the Department of Agricultural Economics and Agribusiness Management, Egerton University. He holds a PhD in Agricultural Economics with teaching and research experience running for many years. Dr. Michael Philliph Musyoka has a PhD in Agricultural Economics and works as a private Economic Development Consultant and Technical Advisor County Government of Makueni (CGM), Kenya.