Open Access

Joachim Grammig, Reinhard Hujer

• This paper provides an empirical assessment of hypotheses that identify causes of demand side constraints of individual labour supply. In a comparative study for the USA and the FRG we focus on analysing the effect of productivity gaps (industry wage growth beyond productivity growth), industry investment intensity and regional labour market conditions on individual employment probabilities. Furthermore, we investigate whether demand side constraints of labour supply can be caused by a spill over from commodity markets. Efficiency wage theory and the theory of inter-industry wage differentials are utilised to derive identifying restrictions that are applicable to the labour supply models for both countries. The econometric contribution of the paper is the derivation and application of a two step estimation method for the class of simultaneous random effects double hurdle models, of which the labour supply model employed in this paper is a special case. To provide the empirical basis for the comparative study, the Panel Study of Income Dynamics and the German Socio-Economic Panel are linked to the OECD’s International Sectoral Database. JEL classification: C33, C34, J64, O57