Richard Blundell

Labor supply: a review of alternative approaches

This chapter surveys existing approaches to modeling labor supply and identifies important gaps in the literature that could be addressed in future research. The discussion begins with a look at recent policy reforms and labor market facts that motivate the study of labor supply. The analysis then presents a unifying framework that allows alternative empirical formulations of the labor supply model to be compared and their resulting elasticities to be interpreted. This is followed by critical reviews of alternative approaches to labor-supply modeling. The first review assesses the difference in-differences approach and its relationship to natural experiments. The second analyzes estimation with non-linear budget constraints and welfare-program participation. The third appraises developments of family labor-supply models including both the standard unitary and collective labor-supply formulations. The fourth briefly explores dynamic extensions of the labor supply model, characterizing how participation decisions, learning-by-doing, human capital accumulation and habit formation affect the analysis of the lifecycle model. At the end of each of the four broad reviews, we summarize a selection of the recent empirical findings. The concluding section asks whether the developments reviewed in this chapter place us in a better position to answer the policy-reform questions and to interpret the trends in participation and hours with which we began this review. q1999 Elsevier Science B.V. All rights reserved.

Quadratic Engel Curves and Consumer Demand

This paper presents a model of consumer demand that is consistent with the observed expenditure patterns of individual consumers in a long time series of expenditure surveys and is also able to provide a detailed welfare analysis of shifts in relative prices. A nonparametric analysis of consumer expenditure patterns suggests that Engel curves require quadratic terms in the logarithm of expenditure. While popular models of demand such as the Translog or the Almost Ideal Demand Systems do allow flexible price responses within a theoretically coherent structure, they have expenditure share Engel curves that are linear in the logarithm of total expenditure. We derive the complete class of integrable quadratic logarithmic expenditure share systems. A specification from this class is estimated on a large pooled data set of U.K. households. Models that fail to account for Engel curvature are found to generate important distortions in the patterns of welfare losses associated with a tax increase.

An Exogeneity Test for a Simultaneous Equation Tobit Model with an Application to Labor Supply

A test of weak exogeneity in the simultaneous equation Tobit model is proposed and illustrated using a female labour supply model estimated using cross-section data. The test statistic can be simply output from any standard Tobit maximum likelihood package, and is asymptotically efficient. The procedure provides consistent estimators for the simultaneous Tobit model whose asymptotic covariance matrix is a simple extension of the usual Tobit formula. We also provide the Lagrange Multiplier test of weak exogeneity.

Market Share, Market Value and Innovation in a Panel of British Manufacturing Firms

This paper examines the empirical relationship between technological innovations, market share and stock market value. New developments in the estimation of dynamic count data models are used to control for unobserved firm specific heterogeneity. We find a robust and positive effect of market share on observable headcounts of innovations and patents although increased product market competition in the industry tends to stimulate innovative activity. Furthermore, the impact of innovation on market value is larger for firms with higher market shares. We argue that our results are consistent with models where high market share firms have incentives to pre-emptively innovate.

Investment and Tobin's Q: Evidence from company panel data

Abstract A Q model of investment is estimated using data for an unbalanced panel of UK companies over the period 1975-86. Correlated firm-specific effects and the endogeneity of Q are allowed for using a Generalised Method of Moments estimator. In the calculation of Q we estimate the tax incentives available to individual companies. Q is found to be a significant factor in the explanation of company investment, although its effect is small and a careful treatment of the dynamic structure of Q models appears critical. In addition to Q, both cash flow and output variables are found to play an independent and significant role.

Individual effects and dynamics in count data models

In this paper we examine the panel data estimation of dynamic models for count data that include correlated fixed effects and predetermined variables.

BIVARIATE ALTERNATIVES TO THE TOBIT MODEL

Abstract This paper discusses some generalisations of the Tobit model that allow for distinct processes determining the censoring rule and the continuous observations. The effect of different behavioural assumptions on the econometric model are examined and the alternatives are constructed. The paper concentrates on diagnostic tests for misspecification that are appropriate in each of our examples. These include tests of independence and normality. The empirical illustrations relate to household demand for clothing and to married womens labour supply. The data are drawn from the Family Expenditure Survey for 1981.

Collective labor supply with children

We extend the collective model of household behavior to allow for the existence of public consumption. We show how this model allows the analysis of welfare consequences of policies aimed at changing the distribution of power within the household. Our setting provides a conceptual framework for addressing issues linked to the “targeting” of specific benefits or taxes. We also show that the observation of the labor supplies and the household demand for the public good allow one to identify individual welfare and the decision process. This requires either a separability assumption or the presence of a distribution factor.

Testing Restrictions in a Flexible Dynamic Demand System: An Application to Consumers' Expenditure in Canada

Traditionally, restrictions on systems of demand equations have been tested using static models, whilst being estimated with time series data. This paper develops a vector time series model of expenditure shares in the context of a singular dynamic demand system. The model allows for non-symmetric and non-homogeneous short run behaviour. The homogeneity and symmetry restrictions are only examined in the long run structure. Results based on Canadian time series data are presented and reject the current practise of static modelling while restrictions suggested by economic theory are not rejected when imposed on the long run structure.

THE INFORMATION-CONTENT OF EQUIVALENCE SCALES

It is well known that equivalence scales, defined as ratios of cost functions between demographically different households, cannot be completely identified from demand data alone. This paper derives the exact components of equivalence scales that are identifiable. It is shown that demand equations alone provide no information about equivalence scales in any one price regime, but that if equivalence scales in any one price regime were known, then demand data can identify the unique true equivalence scales in all other price regimes. Sensible identifying assumptions and implications for the appropriate construction and interpretation of equivalence scales are discussed, and some empirical tests and estimates from UK micro-data are provided.