Semi-democratic regimes are inherently unstable, according to a new study that tests three alternative explanations. The research finds that even when accounting for political instability during emergence and other regime characteristics, semi-demos remain significantly less durable than democracies or autocracies. This confirms "semi-democracies are particularly unstable" as a rare but significant finding in comparative politics. Other results show no systematic difference between military/single-party regimes and their more established counterparts in terms of longevity once democratic levels are controlled.