Measuring Knowledge Spillovers: A Non-appropriable Returns Perspective

A new approach is developed to measure knowledge spillovers by means of proportion of non-appropriable returns to social returns, assuming no specific forms of production and knowledge functions. It is complicated theoretically, but very simple and practical empirically. Using PWT 6.3, we find that: 1. the measure of spillovers is nonlinear to income; 2. spillovers do not exist when income is low, but do exist in higher income groups; 3. the elasticity of knowledge is nonlinear to income; 4. spillovers exist even when the elasticity of output to capital is roughly close to direct measure of capital's share.