Where can I find out more about Crime Mapping?

To exit the Crime Map and read our Top Story on Crime Mapping, click here.

Why did you choose Oxford?

We selected Oxford because it is as close as we could find to a typical British city. In terms of demographics, and particularly in terms of levels and types of crimes, it is typical of the national picture.

Where did the data for the maps come from?

In making this website and the accompanying television series we worked closely with Thames Valley Police. Oxfordshire Fire & Rescue Service, Oxfordshire County Council Trading Standards Department, Oxfordshire Domestic Abuse Services, South Central Ambulance Service, the John Radcliffe Hospital, and Oxford's Crime & Disorder Reduction Partnership, who supplied us with the original data.

The police data covers both recorded crime, which will end up in the official crime figures, and 'incidents' which require police intervention, but were not recorded as crimes as there were insufficient grounds for the police to do so. Beyond the police, data is from incidents attended by other agencies such as Oxford's Ambulance Service.

The Oxford Crime & Disorder Reduction Partnership – or CDRP – is responsible for co-ordinating crime prevention between a number of agencies including police, fire and ambulance services and Oxford City Council. For this purpose the CDRP gathers and uses data from as many different sources as possible.

What time period does the data cover?

The data covers the year from November 2007 to November 2008.

Why are you using heatmaps?

There are a number of methods for mapping crime. Currently, the technique most often used is to map crime data according to geographic areas such as postcodes, census output areas or police 'beat-codes'. The geographic areas chosen to map crime data – such as 'beat-codes' by the police – are often done so because these services deploy their resources according to their chosen geographical areas.

However, as these geographical areas vary greatly in size, when crime data is plotted on a map it is often difficult for a member of the general public to properly see and understand which areas have high or low crime rates. A large area may seem to have more crime than a small area even though this is simply because there is more space and people in that area. A small area with high crime might be hard to spot because it is simply physically smaller on the map, and therefore harder to see.

After extensive consultation with a host of experts in this specialist area, we have decided to use 'heatmaps' to display our crime data, since these offer a clear way for us all to see patterns of crime, without requiring us to have the expert knowledge of crime data analysts, nor a prior knowledge of arbitrary geographical areas. These 'heatmaps' represent the relative amount of crime according to a sliding scale of colour (as detailed in the "Key"), and provide a sense of the area where a type of crime is happening without disclosing the exact location that it took place – so as to protect the anonymity of victims

Heat maps such as these have not previously been used to any great extent in the UK, but have been used in the USA and Canada.

What can I learn from the Crime Map?

Heatmaps are best used for showing patterns of crime – for comparing one area with another, and one type of crime with another – rather than for displaying absolute numbers of crimes.

We have selected a number of different sets of data, including crimes recorded by police, incidents which required police intervention but which cannot be categorised as official 'crimes' (often a much higher number), and incidents recorded by other agencies such as the Ambulance and Fire Service. This allows you to compare different types of crime data, see where crime is higher or lower, and where it is concentrated.

We have also included tools for you to access other information such as key locations in Oxford ("Key Landmarks" and the distribution of licensed premises – pubs, clubs and bars) which can also have an impact on when and where crime happens.

In order to make the heat maps as accurate as possible, they are based on a year's worth of data. This means that any anomalies or spikes in particular places or at particular times are averaged out.

Nevertheless, although we have ensured the data used in these maps is as accurate as possible, it should not be treated as definitive.

Are you showing confidential information?

No, we have been very careful to make sure that no individual or individual address can be identified from the heat maps.

To ensure this, we have used a method called 'postcode sanitisation', which removes the exact locations from the original data, and shifts those locations to the centre of the postcode area in which the incident occurs. Although this makes little visual difference to the final heatmap it makes it impossible to identify any precise address thereby preserving victim privacy. Throughout the course of the development of this map, the BBC and the production team have adhered to strict data protection rules and have had no access to any private or confidential data.

Aren't you worried about highlighting areas of high crime in Oxford?

Surveys have consistently shown that residents of an area would rather know what is happening in their neighbourhood than not, even if it is an area of high crime. Studies have also shown that public-facing crime maps such as these have no effect on issues such as property prices. Indeed Estate Agents in the US are beginning to supply crime maps such as these to potential property purchasers.

Furthermore, the Home Office has now directed all of the Police Authorities of England & Wales to publish local crime information including maps for use by the public.

How does 'Compare My Neighbourhood' work?

The Compare My Neighbourhood tool matches your postcode with similar postcodes in Oxford.

The neighbourhood comparison is done using a demographic database called Acorn, supplied by CACI. Acorn's researchers have placed every postcode in the UK into one of 17 different 'Groups'. These groups are defined by key social and economic indicators such as type of housing (owner-occupied, rented etc), household income, leisure pursuits etc.

For further information on the CACI Acorn database click here.

The Acorn database is used by the British Crime Survey as a useful tool for analysing the British population and its experiences and perceptions of crime.

When you enter your postcode into the tool, it checks which of the 17 Acorn groups your postcode has been assigned to, and then highlights postcodes in Oxford that belong to the same group.

It should be noted that the 'Compare My Neighbourhood' tool is not definitive.. We're not saying that you personally are just like the individuals who live in the area in Oxford your postcode corresponds to. We're suggesting that according to Acorn data, your postcode area is similar to that postcode area in Oxford.

Have you stored my personal information?

No. The Compare My Neighbourhood Tool uses your postcode only once in order to determine which Acorn group your neighbourhood belongs to The information is then immediately erased.

What are the Key Landmarks?

We have selected a series of key landmarks in Oxford – our typical city – to give a sense of where important features – such as the city centre and the main hospital – are located. The Key Landmarks also give a sense of where different types of neighbourhoods – ranging from housing estates to affluent suburbs – can be found across the city.

Who has advised the BBC on this map?

The map has been produced in close consultation with Spencer Chainey, Director of Geographical Information Science at the Jill Dando Institute of Crime Science, University of London. Spencer is one of the UK's leading experts in crime mapping and the methods we have used have been approved by a panel of independent experts in this field.

For more information, please see our list of advisors.

What is Thames Valley Police's non-emergency contact number?

Call 0845 8505505 for all non-emergency enquiries.