Editing Democratic peace theory (section)

====Non-binary classifications====
The above definitions are binary, classifying nations into either democracies or non-democracies. Many researchers have instead used more finely grained scales. One example is the [[Polity data series]] which scores each state on two scales, one for democracy and one for autocracy, for each year since 1800; as well as several others.{{efn|Other such rankings have made by Steve Chan and by Ze'ev Maoz.{{sfn|Maoz|1997}} See also SIPRI{{sfn|SIPRI|n.d.}} and Peter D. Watson Center for Conflict and Cooperation.{{sfn|Peter D. Watson Center for Conflict and Cooperation|n.d.}}}} The use of the Polity Data has varied. Some researchers have done correlations between the democracy scale and belligerence; others have treated it as a binary classification by (as its maker does) calling all states with a high democracy score and a low autocracy score democracies; yet others have used the difference of the two scores, sometimes again making this into a binary classification.{{sfn|Gleditsch|1992}}