Identifying sources of systematic variation in direct price elasticities from revealed preference studies of inter-city freight demand

Freight demand elasticity studies vary significantly in terms of the demand measure, data type, estimation method, commodity type, etc. This wide variation makes it difficult to compare empirical estimates when the differences may arise in part from the methods and data used. In this paper we conduct a comparative analysis to identify systematic sources of influence on direct price elasticity estimates in the context of freight transport, distinguishing between road, rail, and sea transport, using published direct price elasticities from 12 elasticity-derivative studies from five countries. The study focuses on revealed preference elasticities defined by the freight rate for tonnes and tonne kilometres of inter-city freight movements. Systematic sources that explain differences in direct price elasticities include the demand elasticity measure, mode, commodity class, model estimation form, country, and temporal nature of data (e.g., cross-section). Analysts can utilise the model outputs to adjust the empirical evidence from specific studies to control for differences that impact on the behavioural implications of comparative evidence.     

Modelling Risk Perceptions of Stakeholders in Public–Private Partnership Toll Road Contracts

This paper investigates the risk perceptions of key stakeholder groups typically involved in public–private partnership (PPP) toll roads. Risk perceptions have an important impact on these PPP schemes for investing in public infrastructure. However, the nature and extent of risk associated with the specification of a PPP contract that commits contracting parties to deliver on their obligations remain unclear. In the context of major transport infrastructure, such as a new toll road, the often‐cited key risk to investors is the traffic (and hence demand) risk. There are, however, other risks, including political risk and media risk, the latter often causing untold harm resulting in modifications to the planned infrastructure. This paper develops a method to capture evidence on how public sector and private sector partners involved in previous PPPs perceive the levels of risk associated with each risk attribute, as a way of identifying the ex ante risk setting brought to negotiations in PPP toll road investments. Using a sample of 101 experts with contract experience in 32 countries, we develop a stated choice experiment and estimate a discrete choice model to quantify a risk profile index (RPI) to capture the perceived (relative) influence of each dimension of risk, and then identify sources of systematic differences in the RPI as a way of understanding the influence of personal traits and contextual and contractual factors.     

Experimental analysis of choice

Experimental choice analysis continues to attract academic and applied attention. We review what is known about the design, conduct, analysis, and use of data from choice experiments, and indicate gaps in current knowledge that should be addressed in future research. Design strategies consistent with probabilistic models of choice process and the parallels between choice experiments and real markets are considered. Additionally, we address the issues of reliability and validity. Progress has been made in accounting for differences in reliability, but more research is needed to determine which experiments and response procedures will consistently produce more reliable data for various problems.Sawtooth SoftwareDecision Research     

Using stated response choice data to enrich revealed preference discrete choice models

There is growing interest in exploring the view that both revealed preference (RP) and stated preference (SP) data have useful information and that their integration will enrich the overall explanatory power of RP choice models. These two types of data have been independently used in the estimation of a wide variety of discrete choice applications in marketing. In order to combine the two data sources, each with independent choice outcomes, allowance must be made for their different scaling properties. The approach uses a full information maximum likelihood estimation procedure of the hierarchical logit form to obtain suitable scaling parameters to make one or more data sets comparable. We illustrate the advantages of the dual data strategy by comparing the results with those obtained from models estimated independently with RP and SP data. Data collected as part of a study of high speed rail is used to estimate a set of illustrative mode choice models.     

Asymmetric preference formation in willingness to pay estimates in discrete choice models

Individuals when faced with choices amongst a number of alternatives often adopt a variety of processing rules, ranging from simple linear to complex non-linear treatment of each attribute defining the offer of each alternative. In this paper we investigate the presence of asymmetry in preferences to test for reference effects and differential willingness to pay according to whether we are valuing gains or losses. The findings offer clear evidence of an asymmetrical response to increases and decreases in attributes when compared to the corresponding values for a reference alternative, where the degree of asymmetry varies across attributes and population segments.     

Willingness to pay for travel time reliability in passenger transport: A review and some new empirical evidence

This paper reviews and critiques the modelling frameworks and empirical measurement paradigms used to obtain willingness to pay (WTP) for improved travel time reliability, suggesting new directions for ongoing research. We also estimate models to derive values of reliability, scheduling costs and reliability ratios in the context of Australian toll roads and use the new evidence to highlight the important influence of the way that trip time variability is included in stated preference studies in deriving WTP estimates of reliability in absolute terms, and relative to the value of travel time savings.     

An Analytical Framework for Joint vs Separate Decisions by Couples in Choice Experiments: The Case of Coastal Water Quality in Tobago

This paper offers an analytical framework for analyzing joint and separate decisions by couples in the context of choice experiments for nonmarket valuation. It reports results from an attribute-based stated preference study in which members of couples are asked to conduct a choice-experiment first individually and then jointly. The choice context was the selection of which beach to visit while on vacation in Tobago. Available alternatives differed in attributes related to coastal water and beach quality such as level of coastal development and fish abundance. Tests of preference equality are reported and structured so as to identify the intra-couple decision-making patterns under taste heterogeneity with both finite and continuous mixed logit. Results from the latter suggest that women’s preferences are found to be predominant in the joint choice-experiment. Results suggest caution in using individual choice rather than joint couple choice when valuing quality changes impacting on couple activities, such as water and beach quality in Tobago, and call for further research on the topic.     

Combining Sources of Preference Data for Modeling Complex Decision Processes

We review current state-of-the-art practices for combining preference data from multiple sources and discuss future research possibilities. A central theme is that any one data source (e.g., a scanner panel source) is often insufficient to support tests of complex theories of choice and decision making. Hence, analysts may need to embrace a wider variety of data types and measurement tools than traditionally have been considered in applied decision making and choice research. We discuss the viability of preference-stationarity assumptions usually made when pooling data, as well as random-utility theory-based approaches for combining data sources. We also discuss types of models and data sources likely to be required to make inferences about and estimate models that describe choice dynamics. The latter discussion is speculative insofar as the body of literature on this topic is small.