Directional bias in vacation travel

Vacation travel between regions is usually asymmetrical. This causes a problem when one tries to use a gravity model to forecast inter-regional travel. Although researchers have adopted strategies for coping with this problem, none of these strategies adequately resolve the complication of asymmetrical flows. This paper presents a measure of directional bias that accounts for unequal flows between two regions, and applies it to inter-provincial flows in Canada for the years 1968 to 1978. The directional bias appears to be stable over the period considered, and the index can be easily incorporated into forecasting models. Its use will allow researchers to add greater precision and power to their predictive models.