Opportunity for war is measured by great-power status or shared borders

Evidence

For example, opportunity is normally operationalized as either ma­ jor power status OR geographical contiguity. One can see these sub­ stantive factors mentioned in the long quote just above, for example when Maoz and Russett say that countries “too far apart” (i.e., no op­ portunity) AND with no “irreconcilable conflicts of interest” (i.e., no willingness) constitute the set of irrelevant observations. — Gary Goertz, Social Science Concepts, 113

Categorization

• SHARE: Niche tidbit for anyone doing measurement work: ‘irrelevance’ in dyadic war studies literally reduces to two indicator variables, contiguity and major-power status.