This paper investigates the role of model uncertainty in explaining the different findings in the literature regarding the determinants of government expenditure and its components. In particular, we systematically assess the evidentiary support for nine different theories using a novel model averaging method that allows for endogeneity. Our results suggest that the government size and its components are explained by multiple mechanisms that work simultaneously but differ in their impact and importance. Hence, policy makers should avoid relying on any particular model to make policy decisions. More precisely, for general government total expenditure we find decisive evidence for the demography theory and a strong evidence for the globalization and political institution theory. In the case of central government total expenditure, we find that income inequality and macroeconomic policy play a decisive role in addition to demography.

中文翻译：

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衡量政府规模理论的实力

本文研究了模型不确定性在解释有关政府支出及其构成因素的文献中的不同发现方面的作用。特别是，我们使用允许内生性的新型模型平均方法，系统地评估了九种不同理论的证据支持。我们的结果表明，政府规模及其组成部分是由多种同时发挥作用但作用和重要性不同的机制来解释的。因此，决策者应避免依赖任何特定模型做出决策。更确切地说，对于一般政府的总支出，我们为人口统计学理论提供了决定性的证据，为全球化和政治制度理论提供了有力的证据。就中央政府的总支出而言，