Institute for Transport Studies (ITS)

Are we modelling the wrong thing: differences between the psychologists' and the modellers' view of behaviour

Supervisors: Dr Richard Batley, Professor Stephane Hess

Mathematical models representing human behaviour are used extensively in the field of transport and beyond. These models are used to analyse existing choices and forecast likely behaviour in a changing environment, e.g. the provision of new transport facilities, the introduction of new electricity pricing structures or the building of a new hospital.

To a large extent, these models are based on a compensatory approach, in which a person is assumed to make choices by trading off different attributes against one another. As an example, one mode of travel may be faster, but an alternative mode is cheaper; one train will get us to work on time, but the slightly later train is considerably less congested. The values of the different attributes of an alternative all affect that alternative's probability of being chosen, where the negative effect of one attribute may be cancelled out by the more positive effect of another attribute.

A different view of behaviour however exists in various strands of the mathematical psychology literature. Here, evidence suggests that at some people do not in fact engage in compensatory evaluation of alternatives, but make use of various alternative heuristics to arrive at their choices. This could for example involve lexicographic behaviour, the existence of reference points or the presence of thresholds in sensitivities or tolerances.

The aim of this PhD project is to first revisit the limited amount of existing work contrasting and combining the often disparate methodologies from the fields of economics and mathematical psychology. In-depth studies will then be conducted to investigate under which circumstances the assumptions made in traditional approaches may not be justified. Ultimately, the aim is to expand the existing methodological framework to be able to adequately represent decision making processes that are well established in the mathematical psychology literature, but which are largely ignored in the modelling field. By better understanding and representing the underlying behavioural structures, the project will seek to enhance the predictive power of models used to plan the provision and usage of scarce services and resources (such as healthcare, energy and transportation).

While the topic is concerned with the interface between psychology, economics and mathematics, the proposed research will be highly methodological in its nature, and a strong quantitative background will be expected from the student. Some programming skills will be also be desirable.

References – suggested reading

Batley, R. and Daly, A. (2006) On the equivalence between elimination-by-aspects and generalised extreme value models of choice behaviour. Journal of Mathematical Psychology, 50 (5), pp456-467.

Batley, R. and Toner, J. (2003) Elimination-by-aspects and advanced logit models of stated preferences for alternative-fuel vehicles. Proceedings of the European Transport Conference, Strasbourg, October 2003.

Hess, S., Rose, J.M. and Polak, J.W. (2009), Non-trading, lexicographic and inconsistent behaviour in stated preference data, Transportation Research Part B, forthcoming.

Simon, H.A. (1959) Theories of decision-making in economics and behavioral science. American Economic Review, 49 (1), pp253-283.

Train, K.E. (2003) Discrete choice methods with Simulation, Cambridge University Press, Cambridge, MA.

Tversky, A. (1972) Elimination by aspects: a theory of choice. Psychological Review, 79 (4), pp281-299.

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