Chapter 8: Stated Preference Experimental Design Strategies

Stated choice experiments are often used in transportation studies for estimating and forecasting behaviour of travellers, road authorities, etc. Underlying all stated choice studies are experimental designs. Via experimental design theory, the analyst is able to determine when particular attribute level values should be shown to respondents in the choice survey. Conceptually, experimental designs may be viewed as simply nothing more than matrices of numbers that researchers use to assign values to the attributes of the alternatives present within the hypothetical choice situations of stated choice surveys (Figures 1 and 2). The levels shown in these hypothetical choice situations were predetermined from some underlying experimental designs. The attribute level values in these screenshots are related to the attribute levels of a design associated with each of the alternatives, which may differ for each individual as well as over each choice situation. By using experimental design theory, the assignment of these values occurs in some systematic (i.e., non-random) manner. The purpose of this chapter is to describe exactly what it is that determines the systematic processes underlying the assignment of attribute level values to choice situations.