Comprehensive NNP, social welfare, and the rate of return

We show that growth in NNP measured in constant prices indicates welfare improvement, provided that an observable rate of return measure is positive. This is an alternative welfare interpretation of growth in comprehensive NNP compared with that of Asheim and Weitzman [Asheim, B.G., Weitzman, M.L., 2001. Does NNP growth indicate welfare improvement? Economic Letters 73, 233-239] which is based on a Divisia consumer price index.