countries beginning from January 2006. Figure 1 shows the locations of these markets across the four countries as well as the number of monthly observations available for each. Appendix Table A.1 presents a breakdown of the number of markets by country as well as markets across regions of Malawi over the sample period. The price data preview is presented in Figure 2, which shows the national median prices and the timing of the export bans in the respective countries. Over the study period, we find that price levels across all four countries have shown signs of seasonal variation within each year as well as fluctuations across the years. Price levels spiked during the 2007–2008 global food price crisis. Following that, from around 2010 onwards, Mozambique and Tanzania had higher price levels, relative to Malawi and Zambia. The figure also shows the periods during which export bans were in place by each country. During the 2008 food price crisis, when countries were forced to respond to sharp food price inflation, both Malawi and neighboring Zambia and Tanzania imposed export bans. Since 2012, export restrictions have been more active only in Malawi and Zambia. Tanzania’s use of export bans was relaxed until recent years. Mozambique has not imposed any ban during the entire study period.

While the comparison of national average prices may be informative, the empirical analysis adopted to study the impacts of export bans on domestic and relative prices uses market-specific prices in Malawi and pairwise comparison of markets within Malawi and markets in the neighboring countries. We identify the closest and the farthest pairs of markets based on distance and travel time. The imputation of distance and travel time is based on road network data from the HERE API.<sup>3</sup> For our analysis, we locate, for each of the 74 markets in MW, the closest markets in country B (where B is MW, TZ, MOZ, or ZM). MW-MW refers to a market pair where both markets are within Malawi, and MW-TZ, for example, indicates that one of the markets is in Malawi, and the other is across the border in Tanzania.<sup>4</sup> Figure 3 presents the median price dispersion of 327 market pairs, some of which are within Malawi and others across the border in TZ, ZM, and MOZ. The median price dispersion among market pairs within Malawi remains relatively flat across

> 3 The calculation of the travel time between every pair of markets within Malawi and its neighbors is implemented using the Stata package _georoute_ which relies on map data from HERE ((https://developer.here.com/) (Weber and Péclat 2017).

4 The nearest market pairs are identified in the following manner. First, for each of the 74 markets in MW, we identify all possible market pairs (by pairing it with the remaining 73 markets in MW and 79 markets across the border in TZ, ZM, or MOZ) and then impute the travel distance (and travel time) on the existing road network. Second, for market pairs in country B, that is, MW-country B, we identify the nearest market as the one with the decile of travel distance. Using this technique, we identified a total of 327 market pairs and the table below provides a summary of the travel distance. We present results using the lowest decile of travel distance, but the result is similar when we use the lowest quartile of travel distance or even travel time. The number of market pairs varies from 26 pairs in the case of MWMOZ to 112 pairs for MW-ZM. Within Malawi, the number of market pairs is 128.

|Travel distance (km) between<br>market pairs|Mean|Standard deviation|Minimum|Maximum|Number of pairs|
|---|---|---|---|---|---|
|MW-MW|95.1|56.4|24.9|301.0|128|
|MW-MOZ|451.0|112.5|134.6|646.8|26|
|MW-TZ|725.9|156.4|281.8|940.7|61|
|MW-ZM|375.6|126.6|96.7|659.7|112|
|Total|337.1|254.9|24.9|940.7|327|
|Observations|327|||||

Source: Authors’ calculations based on distance and travel time between locations of markets.

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