In this paper we analyze statistical properties of stated preference designs for the scheduling model. The scheduling model is frequently used for estimating the willingness to pay (WTP) for a reduction in schedule delay early or schedule delay late. These WTP values can be used to calculate the costs of travel time variability. Creating a design is not an easy task, since the attributes shown to the respondents are different from the model attributes that are estimated.  Because of this mapping there can be a lot of correlation in the model even if the attributes shown to respondents are designed orthogonally. We create an algorithm to design the choice experiment using measures for efficiency (S-efficiency and WTP-efficiency) for a design dependent on the reference travel time of the traveler. In a simulation we show that the designs based on these criteria perform on average better than orthogonal or fractional factorial designs in terms of efficiency of the WTP.