better at identifying civil conflicts than COW.<sup>12</sup> Finally, along with major civil conflicts, PRIO also codes minor conflicts as those above 25 battle deaths per year. We believe these smaller conflicts provide a relevant complement to the more episodic full blown civil conflicts. In fact the problem with estimating the determinants of a rare event as conflict onset strengthens the importance of adding these smaller conflicts to the database.

One issue with the conflict data is that temporary reductions in the yearly number of casualties (i.e. below 1,000) are automatically counted as peace years. For instance, in the Angolan Civil War (1975-2002) the number of fatalities was below 1,000 in 1991 and 1995, even though the war was continuing with a large number of yearly casualties. To check the sensitivity of the results to this coding procedure, we also construct an additional conflict variable, which defines peace years in between war years as those with a number of battle related deaths that falls below 300. The results presented below for _major conflict onset_ are based on this variable although the results are very similar when using the _major conflict onset_ from PRIO (results available upon request).

We use various trade variables in the empirical analysis. Two of them (i.e. commodities’ export and import prices) rely on a combination of international commodity prices and country-specific trade shares. The former come from data coded by B-B, who combine price data for 65 commodities from various sources, including the IMF International Financial Statistics (IFS), the US Bureau of Labor Statistics (BLS), Global Financial Data (GFD) and additional sources.<sup>13</sup> We complement B-B data with the Commodity Price Data from the World Bank to obtain prices for 73 internationally traded commodities.<sup>14</sup> Using this data we are able to construct the export price index: where _Px_ is defined as the log of the geometric average of the international commodity prices ).<sup>15</sup> Each commodity is weighted by its country -specific average value of exports between _t-k_ and _t-2_ , where in our case k takes the value of 12 or of 4 (see below). jjii (PP ii

> 12 We first checked the conflict instances that were missing in PRIO according to Gersovitz and Kriger (2013) (i.e. Cameroon, Central African Republic, Congo-Brazzaville, Côte d’Ivoire, Kenya (Shifta War, 1963 to 1967), Mali, Niger and Senegal). All of these conflicts, with the exception of the one in Kenya, have been included in the latest versions of the PRIO dataset while they were still missing in COW. As an additional check, we identified those conflict incidences recorded in COW but missing in the PRIO data (e.g. Liberia in 1996). We find that in various instances, these conflict years had been there in earlier versions of the PRIO data but had been removed in the more recent versions, suggesting a frequent process of updating of the conflict episodes in the PRIO dataset.

> 13 See  B-B’s web appendix for the complete list of sources.

> 14 The list of these commodities is available in a web appendix at the end.

> 15 To avoid the effects of different units of measure across commodities, all international commodity prices are normalized to 100 in 2000.

9