MODELLING AND FORECASTING RETAIL PRICES OF MAIZE FOR THREE AGRICULTURAL MARKETS IN TANZANIA

ABSTRACT

This study examined the modelling for maize prices using Autoregressive Integrated

Moving Average (ARIMA) models so as to determine the most efficient and

adequate model for analyzing the maize monthly prices at the Gairo market in

Morogoro Region, Manyoni market in Singida Region and Kibaigwa market in

Dodoma Region. The results indicate that ARIMA (1, 1, 4) model is the most

adequate and efficient model for Gairo market, ARIMA (2, 1, 3) model is the most

adequate and efficient mode1 for Manyoni market and ARIMA (2, 2, 3) model is the

most adequate and efficient model for Kibaigwa market. This was determined by

comparing the various model selection criteria and the diagnostic tests for various

models among them Akaike Information Criteria (AIC) and Bayesian Information

Criteria (BIC) and Mean Absolute Percentage Error (MAPE). Time-series analysis

was done using STATGRAPHICS, EXCEL, R software and SAS JPM. The forecast

results suggest that there are expectations of increasing maize prices in Manyoni

market from July-2018 to March-2019, the maize prices in Kibaigwa market are also

expected to increase with time from January 2018 to February 2019 and the maize

prices at Gairo market are expected to keep on increasing with time from July 2018

to May 2019. A better understanding of maize prices situation and future prices will