2.4. Statistical analysis
Our walking network exposure assessment model automatically calculates AZD-4547 total length, total time and cumulative exposure for each route. To calculate the average pollutant concentration on each route the cumulative exposure was divided by the total time. Subsequently, the absolute and percentage difference in duration and average pollutant concentration was calculated. Quantile regression was used to illustrate the change in pollutant concentration associated with the change in travel time for different quantiles of the study sample (Cade and Noon, 2003 and Koenker and Hallock, 2001).