Agrifood value chains are complex transaction-linked networks: What does this mean for sampling methodology?

by Kate Ambler, Jeff Bloem, Alan de Brauw, and Julia Wagner

Agrifood value chains are an integral part of food systems, moving food from farms where it is produced to retailers where it is sold to consumers. Agrifood value chains can be quite simple—consumers can buy directly from farms at farmers’ markets, for example—or they can be quite complex, involving processing steps on multiple continents before products reach retailers. Yet research often sets aside these distinctions and depicts agrifood value chains as highly stylized and simple—typically as a simplified series of steps involving traders, aggregators, processors, and/or wholesalers between farms and retailers. The most common method for studying multiple intermediary actors within agrifood value chains—“stacked surveys” that randomly sample respondents within each of these steps—follows this simplified approach.

We know that these stylized illustrations oversimplify agrifood value chains—for example, some farmers of a specific crop might sell to a neighbor who then sells in a local market to a larger trader, while other farmers take the crop directly to the trader. Unfortunately, there is little evidence about the complexity of these buying and selling patterns and the implications of this complexity on sampling methodology. To help fill that gap, we use a network-based survey that aims to better capture the range of these relationships within agrifood value chains. The graphic below illustrates descriptive statistics from the survey, depicting buyers and sellers in various value chain interactions by type of actor.