References: Cameron A. Shelton (2007) “The size and composition of government expenditure” Journal of Public Economics, 91 (11–12) Simon Johnson, William Larson, Chris Papageorgiou, Arvind Subramanian.
The paper only lists one way of testing for Wagner’s hypothesis (i.e., analyzing the relation between the share on GDP of government spending and real GDP per capita) when in fact there are many ways of looking at the hypothesis. The authors should include at least a couple of recent ways of testing this law, in addition to the traditional way of testing for it.