Five reasons to be cautious about street level crime data

Lots of ‘street level crime’ #opendata released today on This ought to be another great moment for the #opendata movement, and in one sense it is. The government has stuck to its promise to release this data, and it has forced the police to produce it on time. It is good that politicians now see that opening data will promote a debate and enable citizens to discuss the issues with the professionals. This is the real promise of #opendata: it helps empower people by promoting more active questioning of the issues.

However, this is another example of ‘ugly, early’ and we must look at the data very carefully to see what it is currently good for. Here are 5 reasons to be cautious about the insights it reveals at this stage.

  • The locations used for the map points are somewhat suspect as these quotes from the site indicate. “The location of incidents shown is approximated and indicative only. This is to protect the anonymity of individuals.” “Incidents of crime or anti-social behaviour are mapped to an anonymous point on or near the street where it happened.” What does this mean? If the police shift points around in urban areas then they just move the crime to places that may have had no crime. Press reports eg Guardian top 100 crime streets already suggest that some of these locations are actually surrogates for the real problem nearby. Incidentally, there is no guarantee that they are going to aggregate and report crime to the same points each month, so we won’t be able to compare through time.
  • For privacy reasons data is not shown for “… streets with fewer than 12 postal addresses”. What happens to these crimes… are they shifted next door or do they vanish? This is an arbitrary number to comply with advice from the Information Commissioners’ Office on privacy. But ICO’s advice still applies even if we can get the data from other sources eg Court Service, so these public censorship measures to protect privacy are in reality a sort of ‘moral panic’ about detailing a truth most people already know from other sources.
  • Some data is redacted eg sexual offences, murder. The Metropolitan Police has already released this data to ward level though… and it is easy to cross-reference one murder in one ward to reports in the local press at the same time:
    7:55am Monday 13th December 2010
    Richard Davies Jones, a solicitor from Woodfield Lane, Lower Ashtead, was charged in the early hours of this morning with the murder of 31-year-old Laura Grace Emily Davies Jones, a social worker from the same address. Its a simple job to match this name in the Electoral roll. Local aggregators already gather and publish this eg Belocal. Just put into your postcode and Twitter name and you get a semi-real time feed of local news including crime reports.
  • The data covers reported crimes not convicted criminals ie some of this activity turned out not to be crime. In some places people may be more or less disposed to report crime.
  • There is nothing here on the burden of policing in each area, so in many cases two areas with the ‘same crime levels’ side by side will have radically different experiences of crime and policing.

So. It is great to see the data released, but this is only the first step. We need to support the police to better locate the crime and we need better visualisation of the data to set it in the context of demographics, policing and local geography. To contribute to this process Placr has developed a multiresolution crime browser for the data. In these maps you always get an overview of the patterns geographically and of each type of crime within the total until you zoom to the full point level detail. It gives a wonderful overview of the crime patterns within cities, exposing each neighbourhood’s experience of crime. Matching this with ‘burden of policing’ data would allow us to see if police time is being spent where the crime reports are.

There are now a bunch of research questions including where is there ‘excess’ crime given the density of population or poverty/wealth indicators? If we build on this release and enhance the data, perhaps the police can build a new relationship with the communities they serve through a new dialogue, and that would be a big win.


2 thoughts on “Five reasons to be cautious about street level crime data

  1. Sarah Drummond

    Hi Jonathan,

    Great post, Im currently collecting open data examples/work for a conference in March. Like your thinking, would be good to chat more about police and geo locations, do you have time to have a chat on the phone?



    (email is

  2. Nick Malleson

    Hi Jonathan,

    Really interesting post. You might be interested in a project I’m working on called GeoCrimeData ( We’re going to use existing street, building and demographic data to try to elucidate some of the demographic and local geographic factors that are important to provide the context behind these figures.

    All the output data from the project will be as publicly available as far as possible.

    Kind regards,
    Nick Malleson

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