The Effect of Arms Trade on Defense Spending According to the Level of Democracy: Panel Smooth Transition (PSTR) Model.

Based on theoretical foundations, the effect of arms trade on defense spending is ambiguous and influenced by various strategic, security and political factors. One of these factors is democracy. In this regard, this paper investigates the threshold effects of arms trade on defense spending in 30 selected countries for the period of 1995 to 2018, using the Panel Smooth Transition Regression (PSTR) model as one of the most prominent regime-switching models. For this purpose, democracy net is used as a transition variable. The linearity test results indicate strongly nonlinear relationship among variables under consideration. Moreover, considering one transition function and one threshold parameter, as a two-regime model, is sufficient to specification of nonlinear relationship among variables. The results indicate that threshold value is 4.75 percent and the estimated slope parameter is 0.61. In the first regime, the arms import has a positive and small effect on defense spending; that after crossing the threshold level and entering the second regime, this positive effect has decreased. Also, arms export has a positive effect on defense spending in the first regime; But after crossing the threshold level, in the second regime, this positive influence changes its sign and becomes negative. Based on other results, after crossing the threshold level of democracy and being in the second regime, the positive effect of the variables of GDP, population, income from natural resources and the conflict index, decrease (while maintaining the sign) and the negative effect of the health spending variable increases. These results show that the level of democracy plays an important role in the effect of the arms trade on defense spending and in general the effect of the variables included in the defense spending function.