The study of coup-proofing holds significant importance in political science as it offers insights into critical topics such as military coups, authoritarian governance, and international conflicts. However, due to the multifaceted nature of coup-proofing and empirical inconsistencies with existing indicators, there is a need for a more profound understanding and a new measurement methodology. We propose a new measure of the extent of coup-proofing, utilizing a Bayesian item response theory. We estimate the extent of coup-proofing using a sample of 76 countries between 1965 and 2005 and theoretically relevant observed indicators. The findings from the estimation demonstrate that the extent of coup-proofing varies across regime type, country, and time. Furthermore, we verify the construct validity of our measurement.

In 1833-1874, Spain suffered 0.7 coups per year. By contrast, the Restoration (1874-1923) saw the eradication of successful coups. This can be partially attributed to the turno pacífico, which allowed the main political parties to alternate in office without dragging the military into politics. We suggest, however, that the reduction in coup risk was also associated with a conscious budget policy. This, though, did not rely on increases in total military expenditure (which actually stagnated during most of the Restoration), but on the steady improvement of officers' remunerations and promotions. This strategy was probably detrimental to Spanish military capacity abroad, but was consistent with the objective of keeping the military out of politics.