4 Theoretically, the relationship between aging of the population and the growth rate is not uniquely determined, but there is a close relationship between aging of the population and government spending. For this reason, if it is assumed that aging of the population and the growth rate have a negative correlation and this relation is not included in the formulation, bias could enter into the estimate influencing the correlation between the size of government spending and the growth rate in the negative direction. However, in the present estimate, the aging factor was not significant.