Experimental Economics and the Theory of Decision Making Under Risk and Uncertainty

Following a brief review of the main experimental work into the economics of risk and uncertainty, both static and dynamic, this paper reports the results of an experiment testing one of the key assumptions of the theory of dynamic economic behaviour—that people have a plan and implement it. Using a unique design which enables the plan (if one exists) to be revealed by the first move, the experiment was implemented via the Internet on a subset of the University of Tilburg's ongoing family expenditure survey panel. The advantages of using such a set of subjects for the experiment are twofold: the demographic characteristics of the set are known and therefore demographic inferences can be made; the representativeness of the set is known and therefore inferences about populations can be made. The results suggest that at least 36% of the subjects had behaviour inconsistent with the hypothesis under test: that people formulate plans and then implement them. Interestingly demographic variables are unable to explain the consistency or inconsistency of individuals. One conclusion is that subjects simply make errors. An alternative conclusion, consistent with previous experimental research, is that people are unable to predict their own future decisions. The implications for dynamic theory (particularly relating to savings and pensions decisions) are important.     

Context matters

Eliciting the level of risk aversion of experimental subjects is of crucial concern to experimenters. In the literature there are a variety of methods used for such elicitation; the concern of the experiment reported in this paper is to compare them. The methods we investigate are the following: Holt–Laury price lists; pairwise choices, the Becker–DeGroot–Marschak method; allocation questions. Clearly their relative efficiency in measuring risk aversion depends upon the numbers of questions asked; but the method itself may well influence the estimated risk-aversion. While it is impossible to determine a ‘best’ method (as the truth is unknown) we can look at the differences between the different methods. We carried out an experiment in four parts, corresponding to the four different methods, with 96 subjects. In analysing the data our methodology involves fitting preference functionals; we use four, Expected Utility and Rank-Dependent Expected Utility, each combined with either a CRRA or a CARA utility function. Our results show that the inferred level of risk aversion is more sensitive to the elicitation method than to the assumed-true preference functional. Experimenters should worry most about context.     

EXPERIMENTAL EVIDENCE ON ENGLISH AUCTIONS: ORAL OUTCRY VERSUS CLOCK

This paper tests experimentally, in a common value setting, the equivalence between the Japanese English auction (or clock auction) and an oral outcry auction where bidders are allowed to call their own bids. We find that (i) bidding behaviour is different in each type of auction, but also that (ii) this difference in bidding behaviour does not affect significantly the auction prices. This lends some support to the equivalence between these two types of auction. The winner's curse is present: overbidding led to higher than expected prices (under Nash bidding strategies) in both types of auction. Although interesting and encouraging, the results clearly indicate that further research is necessary, particularly with a modified experimental design.     

A comparison of the estimates of expected utility and non-expected-utility preference functionals

This paper extends the literature on the estimation of expected utility and non-expected-utility preference functionals (and the consequent exploration of the superiority of non-expected-utility over expected utility preference functionals) to a comparison of two different ways (pairwise choice and complete ranking) of experimentally obtaining data on such preferences. What is revealed is that the magnitude of the subject error is clearly conditional on the elicitation method used and, rather alarmingly, that the preference functional apparently employed by the subject may also be conditional on the elicitation method.     

The effect of unemployment insurance on the riskiness of occupational choice

This paper examines the effect of unemployment insurance on the riskiness of occupational choice by postulating a model of job search in which job offers have two characteristics; their wage and their security of tenure. Two versions are considered: a general case in which the unemployment benefit is earnings-related, and a special case in which the benefit is of a flat-rate form. Of particular interest in the paper is the individual's desired trade-off between wage and security of tenure, and how this trade-off is affected by the type of insurance scheme in operation. Perhaps surprisingly, we find that an earnings-related scheme encourages risk-taking behaviour by the poor, and risk-avoiding behaviour by the rich; in contrast, a flat-rate scheme neither encourages nor discourages risk-taking.     

Does money impede convergence?

Inspired by Clower’s conjecture that the necessity of trading through money in monetised economies might hinder convergence to competitive equilibrium, and hence, for example, cause unemployment, we experimentally investigate behaviour in markets where trading has to be done through money. In order to evaluate the properties of these markets, we compare their behaviour to behaviour in markets without money, where money cannot intervene. As the trading mechanism might be a compounding factor, we investigate two kinds of market mechanism: the double auction, where bids, asks and trades take place in continuous time throughout a trading period; and the clearing house, where bids and asks are placed once in a trading period, and which are then cleared by an aggregating device. We thus have four treatments, the pairwise combinations of non-monetised/monetised trading with double auction/clearing house. We find that: convergence is faster under non-monetised trading, implying that the necessity of using money to facilitate trade hinders convergence; that monetised trading is noisier than non-monetised trading; and that the volume of trade and realised surpluses are higher with the double auction than the clearing house. As far as efficiency is concerned, monetised trading lowers both informational and allocational efficiency, and while the double auction outperforms the clearing house in terms of allocational efficiency, the clearing house is marginally better than the double auction in terms of informational efficiency when trade is through money. Crucially we confirm the conjecture that inspired these experiments: that the necessity to use money in trading hinders convergence to competitive equilibrium, lowers realised trades and surpluses, and hence may cause unemployment.     

Search for rules for search

This paper presents the findings of some preliminary ‘laboratory’ investigations into ‘actual’ search behavior. Specifically we looked at situations in which searchers' initial information about the distributions was negligible. It seemed likely that simple ‘rules of thumb’ would be used in such situations. Our findings confirmed this view: we identified five such rules which between them ‘accounted’ for a high proportion of observed behaviour. Moreover, these rules although not ‘optimal’) appear to be reasonably good and may be fairly robust; jointly, they may constitute a better explanation (and predictor) of actual search behaviour than do the currently popular supposedly optimal rules.     

Are optimal search rules reasonable? and vice versa? (And does it matter anyway?)

The Economics of Search has made rapid progress in recent years and its results have contributed siginificantly to economic knowledge. Recent work has been particularly marked for the steadily increasing realism of the assumptions describing the environment surrounding the searcher. However, concomitant with this improvement has been a steady growth in the technical complexity of the problem supposedly solved by the searcher. Indeed, many of the recent models are so complicated that their solutions are beyond the capacity of even modern-day computers. After elaborating on this impracticability of optimal search rules, the paper goes on to consider two more realistic and practical alternatives — the adoption of either ‘suboptimal’ or ‘reasonable’ rules. Paradoxically, reasonable rules may, in some circumstances, be better than ‘optimal’ rules. The paper contains a preliminary discussion of what might be meant by ‘reasonable’ behaviour, and shows that a minimal set of criteria for reasonableness leads to the major qualitative conclusions at a market level of optimal search theory.