In the Lucas-Rapping (1969) model of the labour market, fluctuations in unemployment represent individuals optimally adjusting their labour supply behaviour in response to fluctuations in wage rates over the business cycle. In this paper I propose and implement a misspecification test of the Lucas-Rapping treatment of unemployment as labour supply behaviour using panel data. This test extends previous such work with micro data by simultaneously allowing for intertemporal substitution, uncertainty and endogenous unemployment. Using the standard specification of intertemporal labour supply behaviour, I find strong evidence against this interpretation of unemployment. There are two possible interpretations of the test results. The first is that it is necessary to turn to alternative models of the labour market in which unemployed workers are off a supply function. The second is that the test results indicate the necessity of moving to more complex models of intertemporal substitution. However, given current econometric techniques and data sets, these alternative models of intertemporal substitution will be extremely difficult to test.

This study proposes and implements a method of labour supply estimation which is appropriate when the sample contains unemployed and underemployed workers. The estimation method consists of excluding unemployed and underemployed workers from the sample and then using (to avoid selection bias) an extension of Heckman's approach to the case where two correlated selection rules generate the sample. Hausman's specification test is then used to determine whether ignoring constrained workers has led to biases in traditional labour supply estimates, and the empirical results suggest that previous estimates of several important parameters are biased. Since the biases go in the direction that would be predicted by the hypothesis that the unemployed and underemployed are constrained, the results support this hypothesis.

The authors address two questions using experimental data on disadvantaged women. First, what is the impact of being offered Job Training Partnership Act classroom training on the duration of unemployment and employment? Second, what is the effect of actually participating in this training on the length of such spells? Belonging to the treatment group shortens unemployment spells but has no effect on employment spells. Actually participating in training has a larger positive effect on the exit rate from unemployment than the effect of simply being a member of the treatment group. Ignoring the endogeneity of actual training in estimation substantially underestimates its effect.