Seattle’s crime was highest in the city centre during the summer of 2014. Using 32,000+ crime reports collected from June to July as part of the Seattle Summer 2014 dataset, we constructed a heatmap overlaid on top of a map of Seattle. A significant “hot spot” can clearly be seen in the centre of the city. In the North end, we observe a cluster of smaller hot spots. The heatmap’s use of position and hue communicates both the distribution of the data and its frequency or intensity.

Fig 1. Seattle Crime Heatmap, Summer 2014

Fig 1. Seattle Crime Heatmap, Summer 2014

Summarized Offense Description

Next we examine the pattern of common crimes in the city centre. Focusing on the Summarized Offense Description field, we restrict our dataset to only the top 10 summarized offenses. Crime reports are plotted on a map of the city centre, coloured by offense. We further facet the plot by month. This figure allows us to see the distribution of common crimes in the core, and the pattern of that distribution across time. These plots use color to highlight a categorical variable and temporal facetting to illustrate change.

Fig 2. Seattle Top Crimes Monthly, Summer 2014

Fig 2. Seattle Top Crimes Monthly, Summer 2014

Now we try to compare the difference between Seattle and SF city, besides the visualization on gmap, we also want to explore some statistics difference.

In order to compare crimes statistics between two major US west-coast cities, San Francisco and Seattle, we summarised the counts, by hour, and plotted them. The title of each facet denotes the week number.

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One immediate observation is that the hourly crime counts between the two cities track very closely. However, there is one period where the rates differ significantly: crime rates for Seattle are subdued around on Independence day. This “crime armistice”, highlighted in the chart below, starts at 3am on July 4th and ends at 7pm.

One possible explanation could be demographic differences between San Francisco and Seattle. The high cost of living in San Francisco might make it more difficult for families to spend July 4th together, whereas Seattle dwellers are more likely to spend the holiday with their families. Perhaps Seattle’s miscreants simply took the day off.

The types of crimes differ between the two cities. The chart below compares the types of crimes in both cities. The most frequently occuring incident in San Francisco is Larceny/Theft, whereas in Seattle the most commonly reported crime is car prowling.

Reproducibility

This report was produced using an R Markdown script, a feature of the R programming language that allows for a “literate” programming style which mixes text with executable code. The data set is available here.