Underreported trips, a non-negligible empirical effect of traditional survey methods – A new weighting procedure of data enriching to overcome this bias

Travel behavior surveys are essential for a fact based transport policy. But they suffer notoriously from unreported trips. Depending on the mode of transport the amount of underreported trips is estimated in the range up to 40%. An exact determination of underreporting is difficult, because the "underlying truth" is generally latent. One solution is to combine traditional travel survey methods with GPS-based techniques for a representative sub-sample. The result provides patterns of mobility both from the traditional survey for the whole sample as well as from the GPS-survey, which can be used for a weighting procedure to eliminate the bias.