Market connectedness and price spillovers in Ghanaian maize and yam markets: Implications for food security

Integrated staple food markets are essential for food security in sub-Saharan Africa, where national production is often sufficient but spatial disparities limit access for households in deficit regions. This study examines price connectedness in maize and yam markets across ten major regions in Ghana and assesses how transmission patterns respond to domestic and global shocks. Using monthly wholesale prices from January 2006 to December 2024, we employ a dynamic Quantile Vector Autoregression framework to estimate spillovers across the full distribution of price movements. The results show strong integration in maize markets, with total dynamic connectedness averaging 92 %. Major assembly and transit markets, including Kumasi, Techiman and Bolgatanga, consistently transmit price shocks, while coastal consumption markets such as Accra and Takoradi receive them. Yam markets exhibit weaker and more variable integration, with an average connectedness of 87 % and a more dispersed structure of price leadership across regions. For both commodities, connectedness strengthened during the 2008 food price hikes, whereas connectedness during the COVID-19 period was uneven and volatile. In contrast, political regime changes in 2009 and 2017 do not generate substantial shifts in market connectedness, highlighting the dominant role of structural supply chains and trader coordination over short-term political events. The findings identify regional markets where households face greater exposure to price volatility and highlight the importance of spatially targeted investments in transport, storage and market coordination alongside measures to manage shock transmission and reduce vulnerability to price volatility and unequal food access.