Consumption and saving behaviour: modelling recent trends

This paper illustrates recent trends in household consumption and personal savings in the UK and the US and discusses some theoretical models that can be used to interpret them. The trends in these two countries are interesting for several reasons. The decline in personal saving rates in the US during the 1980s is an unresolved puzzle. The corresponding variable in the UK has undergone large fluctuations, as have several other variables ranging from projected demographic trends to female labour supply. This paper stresses the need to analyse individual data to shed some light on these aggregate trends. It also stresses the need to have a sound structural model to interpret observed patterns in the data. The theoretical framework discussed throughout the paper is the life-cycle model, which views consumption and saving decisions as part of a dynamic optimisation process. The development of the model and the current research agenda and ways that it can be enriched with various degrees of sophistication are discussed. Particular attention is devoted to the discussion of the most recent developments.

Conditional cash transfers, women and the demand for food

We examine the effect of large cash transfers on the consumption of food by poor households in rural Mexico. The transfers represent 20% of household income on average, and yet, the budget share of food is unchanged following receipt of this money. This is an important puzzle to solve, particularly so in the context of a social welfare programme designed in part to improve nutrition of individuals in the poorest households. We estimate an Engel curve for food. We rule out price increases, changes in the quality of food consumed and homotheticity of preferences as explanations for this puzzle. We also show that food is a necessity, with a strong negative effect of income on the food budget share. The decrease in food budget share caused by the large increase in income is cancelled by some other relevant aspect of the programme so that the net effect is nil. We argue that the program has not changed preferences and that there is no labelling of money. We propose that the key to the puzzle resides in the fact that the transfer is put in the hands of women and that the change in control over household resources is what leads to the observed changes in behaviour.Demand, conditional cash transfer, Engel curves, income elasticities, QUAIDS, food, nutrition.

Estimating Euler equations

In this paper we consider conditions under which the estimation of a log-linearized Euler equation for consumption yields consistent estimates of preference parameters. When utility is isoelastic and a sample covering a long time period is available, consistent estimates are obtained from the log-linearized Euler equation when the innovations to the conditional variance of consumption growth are uncorrelated with the instruments typically used in estimation. We perform a Montecarlo experiment, consisting in solving and simulating a simple life cycle model under uncertainty, and show that in most situations, the estimates obtained from the log-linearized equation are not systematically biased. This is true even when we introduce heteroscedasticity in the process generating income. The only exception is when discount rates are very high (e.g. 47% per year). This problem arises because consumers are nearly always close to the maximum borrowing limit: the estimation bias is unrelated to the linearization and estimates using nonlinear GMM are as bad. Across all our situations, estimation using a log-linearized Euler equation does better than nonlinear GMM despite the absence of measurement error. Finally, we plot life cycle profiles for the variance of consumption growth, which, except when the discount factor is very high, is remarkably flat. This implies that claims that demographic variables in log- linearized Euler equations capture changes in the variance of consumption growth are unwarranted.

Oportunidades: Program Effect on Consumption, Low Participation, and Methodological Issues

In this paper we estimate the effect of the Mexican conditional cash transfer program, Oportunidades, on consumption, and we explore some issues related to participation to the program and to the estimation of treatment effects. We discuss the comparability of treatment and control areas, provide evidence that the expected transfer may not be sufficiently high to induce many eligible households to participate, and find positive effects on consumption.program evaluation, consumption, matching, Oportunidades

Risk Sharing in Private Information Models with Asset Accumulation: Explaining the Excess Smoothness of Consumption

We derive testable implications of model in which first best allocations are not achieved because of a moral hazard problem with hidden saving. We show that in this environment agents typically achieve more insurance than that obtained under autarchy via saving, and that consumption allocation gives rise to 'excess smoothness of consumption', as found and defined by Campbell and Deaton (1987). We argue that the evidence on excess smoothness is consistent with a violation of the simple intertemporal budget constraint considered in a Bewley economy (with a single asset) and use techniques proposed by Hansen et al. (1991) to test the intertemporal budget constraint. We also construct closed form examples where the excess smoothness parameter has a structural interpretation in terms of the severity of the moral hazard problem. Evidence from the UK on the dynamic properties of consumption and income in micro data is consistent with the implications of the model.

Stochastic Components of Individual Consumption: A Time Series Analysis of Grouped Data

In this paper we propose a method to characterize the time series properties of individual consumption, income and interest rates using micro data, as studies in labour economics have characterized the time series properties of hours and earnings. Our approach, however, does not remove aggregate shocks. Having estimated the parameters of a flexible multivariate MA representation we relate the coefficients of our statistical model to structural parameters of theoretical models of consumption behaviour. Our approach offers a unifying framework that encompasses the Euler equation approach to the study of consumption and the studies that relate innovations to income to innovations to consumption, such as those that have found the so-called excess smoothness of consumption. Using a long time series of cross sections to construct synthetic panel data for the UK, we estimate our model and find that the restriction of Euler equations are typically not rejected, while the data show ‘excess smoothness’.

Pension wealth and household saving: evidence from pension reforms in the UK

Using three major UK pension reforms as natural experiments we investigate the relationship between pension saving and discretionary private savings. Unlike most differences-in -differences approaches which rely on average differences between the control and the treatment group, we use economic theory to model the response of each individual household. The model permits us to use both time- series and cross-sectional variation in a consistent way to identify the behavioural response. The study is based on data from the Family Expenditure Survey. A measure of pension wealth is not observed, but we estimate it by applying the rules of the pension system to observed individual characteristics. The changes in pension wealth as a result of the reforms are substantial. The empirical analysis suggests that the earnings -related tier of the pension scheme has a negative impact on private savings with substitution elasticities approaching –1.0. The impact of the flat-rate tier of the scheme is found not to be significantly different from zero.

Differential mortality in the UK

In this paper we use the two waves of the British Retirement Survey (1988/89 and 1994) to quantify the relationship between socio-economic status and health outcomes. We find that, even after conditioning on the initial health status, wealth rankings are important determinants of mortality and the evolution of the health indicator in the survey. For men aged 65 moving from the 40th percentile to the 60th percentile in the wealth distribution increases the probability of survival by between 2.4 and 3.4 percentage points depending on the measure of wealth used. A slightly smaller effect is found for women of between 1.5 and 1.9 percentage points. In the process of estimating these effects we control for non-random attrition from our sample. British welfare reform debate in recent years. This debate is informed by tax-benefit modelling, yet accurate modelling of Family Credit is fraught with potential problems. The main model input data are found to under-sample Family Credit recipients considerably, but those who it does sample seem representative of the Family Credit recipient population. Substantial mismatch is found between those reporting Family Credit receipt and those modelled as en Titled. We show that regression techniques can be used to adjust model results for the fact of non take-up, but that data constraints leave no obvious way to deal with the equally significant problem of famlies who receive benefit but are not modelled as en titled. The difficulties posed by the input data's under-sampling and by the significant number of claimants without modelled en Titlement lead us finally to consider the use (and the limitations) of calibrating results.

Relative Wage Movements and the Distribution of Consumption

We analyze how relative wage movements across birth cohorts and education groups during the 1980s affected the distribution of household consumption. The analysis integrates the labor economics literature on time variation in the wage structure with the consumption insurance literature. In contrast to previous tests of consumption insurance, we examine the impact of systematic, publicly observable shifts in the hourly wage structure. To circumvent the extreme scarcity of longitudinal data with high quality information on both consumption and labor market outcomes, we draw upon the best available cross-sectional data sources to construct synthetic panel data on consumption, labor supply and wages. We find that low-frequency movements in the cohort-education structure of pre-tax hourly wages drove large changes in the distribution of household consumption. The results constitute a spectacular failure of the consumption insurance hypothesis, and one that is not explained by existing theories of informationally constrained optimal consumption allocations. We also develop a procedure for assessing the welfare consequences of deviations from full consumption insurance and, in particular, from the failure to insulate the consumption distribution from relative wage shifts across cohort-education groups. For a coefficient of relative risk aversion equal to two, fully insulating households from group-specific endowment variation would raise welfare by an amount equivalent to a uniform 2.7% consumption increase.

Is Consumption Growth Consistent with Intertemporal Optimization? Evidence from the Consumer Expenditure Survey

In this paper we show that some of the predictions of models of consumer intertemporal optimization are not inconsistent with the patterns of non-durable expenditure observed in US household-level data. Our results and our approach are new in several respects. First, we use the only US micro data set which has direct and complete information on household consumption. The microeconomic data sets used in most of the consumption literature so far contained either very limited information on consumption (like the PSID) or none at all, in which case consumption had to be obtained indirectly from income and changes in assets. Second, we propose a flexible and novel specification of preferences which is easily estimable and allows a general treatment jof multiple commodities. We show that aggregation over commodities can be important, both theoretically and in practice. Third, we present empirical results that show that it is possible to find a reasonably simple specification of preferences, which controls for the effects of changes in demographics and labor supply behavior over the life cycle and which is not rejected by the available data. On our preferred specification, we obtain sharp estimates of key behavioral parameters (including the elasticity of intertemporal substitution) and no rejections of theoretical restrictions. Our results contrast sharply with most of the previous evidence, which has typically been interpreted as rejection of the theory. We show that previous rejections can be explained by the simplifying assumptions made to derive empirically tractable equations. We also show that results obtained using food consumption or aggregate data can be extremely misleading.