Collect-event function available with the spatial statistic tool was used for performing the function,
which in turn will yield a new weighted point feature class with a field ICount that indicates the sum of
all the accidents happened in a unique geographic location. This weighted point feature was used as the
input for running the hotspot function (Getis-Ord GI*) to identify whether features with high values or
features with low values tend to cluster in the study area. This tool works by looking at each feature
within the context of neighbouring features. If a feature's value is high, and the values for all of it's
neighbouring features is also high, it is a part of a hot spot. The local sum for a feature and its neighbours
is compared proportionally to the sum of all features; when the local sum is much different than the
expected local sum, and that difference is too large to be the result of random chance, a statistically
significant Z score is the result [21,25,26]. The statistical equation for calculating Gi and Gi* can be
written as,