ISO3 alphanumeric
1 for contiguity
1 for common official of primary language
1 if a language is spoken by at least 9% of the population in both countries
1 for pairs ever in colonial relationship
1 for common colonizer post 1945
1 for pairs currently in colonial relationship
1 for pairs in colonial relationship post 1945
1 if countries were or are the same country
simple distance (most populated cities, km)
simple distance between capitals (capitals, km)
weighted distance (pop-wt, km)
weighted distance (pop-wt, km) CES distances with theta=-1