Article ID: | iaor20103557 |
Volume: | 56 |
Issue: | 4 |
Start Page Number: | 716 |
End Page Number: | 723 |
Publication Date: | Apr 2010 |
Journal: | Management Science |
Authors: | Ingolfsson Armann, Budge Susan, Zerom Dawit |
Keywords: | location |
Using administrative data for high-priority calls in Calgary, Alberta, we estimate how ambulance travel times depend on distance. We find that a logarithmic transformation produces symmetric travel-time distributions with heavier tails than those of a normal distribution. Guided by nonparametric estimates of the median and coefficient of variation, we demonstrate that a previously proposed model for mean fire engine travel times is a valid and useful description of median ambulance travel times. We propose a new specification for the coefficient of variation, which decreases with distance. We illustrate how the resulting travel-time distribution model can be used to create probability-of-coverage maps for diagnosis and improvement of system performance.