I recently spent some time browsing through http://data.nsw.gov.au. One interesting dataset I came across was this from the NSW Bureau of Crime Statistics and Research. It gives coordinate level data for non-domestic assaults and robberies in the Sydney Local Government Area (LGA) between January 2013 and March 2016. All the information discussed in this post uses this dataset.
Seeing this cool map by Andy Woodruff, inspired me to see if there were any similar interesting patterns in the crime data.
I chose to look only at the robbery category of crimes. The animation below displays robberies occurring in a particular hour of the day over January 2013 to March 2016. On the legend, 0 represents 12-1am, 1 represents 1-2am, and so on.
Robberies in Sydney Local Government Area
There are two main impressions I get from this animation:
One is the temporal variation, robberies seem to peak late at night and in the early hours of the morning, dropping off rapidly in the morning and day time.
The other is spatial variation, the suburbs of Sydney, Surry Hills and Rushcutters Bay seem to have particularly high levels of robberies.
It can be hard to know how accurate an impression an animated map like this gives, because it is constantly moving. The discussion below aims to corroborate these impressions and therefore test the ability of the animation to tell an accurate story.
Number of Robberies in hour brackets, Sydney LGA
The line graph matches the impression given by the animation that robberies are significantly lower during the daytime.
Number of Robberies per postcode, Sydney LGA
This map shows that the 2000, 2010 and 2011 postcodes have the highest number of robberies. This broadly agrees with the impressions I discussed above from the animated map.
This all suggests that the impressions created by the animated map are at least somewhat accurate.
There are some limitations to keep in mind with this data. For one, some suburbs do not lie entirely within the Sydney LGA, and so crimes that occur in these suburbs, but outside the Sydney LGA, will not be represented in the maps.
Another consideration is that not all coordinates are exact, some are based on cross streets, parks, or even just a suburb.