Two peaks in the evolutionary landscape of political regimes.

We noted the source (‘From’) and target (‘To’) polity scores for all historical transitions in polity scores of all nations over all years present in the Polity IV data set. Since we only registered changes, the diagonal (i.e. 10→10, 9→9, 8→8, etc.) contains empty cells that are smoothed over in the graph. As the graph illustrates, changes in regimes tend to occur within autocratic or democratic types of regimes, and only seldom between them, or elsewhere in the space of possible transitions.