The crime data reported here has been provided by Devon and Cornwall Police and is based on aggregated recorded crime data extracted from the Force Crime information System (CIS).

There may be a difference between Amethyst data and the police force published statistics based on two influencing factors: Only crimes that are assigned an accurate geographical location are included in the Amethyst data set, and the way a crime is recorded can change or be non-crimed after the record is initially created. Comparison of mapped data against police data may show a discrepancy and vary between 0% and 4% depending of crime type.

Crime maps and statistics effectively inform members of the community of the number, rate and geographical location of defined crime types at a ward level, allowing users to examine and compare levels and trends across the county. They also empower communities to hold local police and partners to account for what is happening and encourage active citizenship through enabling informed involvement at a local level.

Maps are colour-ranked according to the level of crime within each ward, presenting an effective visualization of crime rates. Crime levels are categorised in the Crime Explorer from A (Low) coloured in pale yellow to E (High) coloured darker red.

There are 121 wards within Cornwall. They vary significantly in size and population (the average for England is 5500 people per ward). We have included the population of each Ward when you click on one in the Crime Explorer. In some cases Wards may appear to have a relatively large number of crimes but, because there is a larger resident population, the crime rate remains relatively low. It is the crime 'Rate' rather than total number (often described as 'Count') that defines the Crime Level map grouping into which a ward falls.

The mapping approach used here could suggest that crime levels are the same across a whole ward. This may not be the case. Wards vary considerably in size - urban wards tend to be much smaller than rural wards. Levels of crime can vary significantly within a single ward - one part of a ward may be a crime 'hotspot' while the rest may have very little crime. This variation within wards is not reflected on the Crime Explorer map but is considered by analysts working in the Amethyst team.

The map classes are based on a quantile classification. This distributes a set of values, for example Crime Rates for Violent Crime for all wards in Cornwall, into groups that contain an equal number of values. We are using 5 groups (also called a 'quintile classification'). This method places the same number of data values in each class. It will never have empty classes or classes with too few or too many values. It is attractive in that this method always produces distinct map patterns. Map classifications based on a 'statistical mean' suffer from problems with data of this kind as the mean can be easily skewed by extreme values. Crime rates in central areas of towns and cities are often artificially high (and therefore 'extreme') due to the relatively low number of people living there and the high number of visitors that come into these areas on a temporary basis.

The Crime Profile table provides a summary of the level and current change of crime across a range of different crime types for your area of interest.

Crime Type: these are defined by the Home Office and described in more detail below. We are using ‘quarterly data’ where crimes have been aggregated for a period of 3 months. It is important to compare changes in crime levels with the same period from a previous year.

Grade: displays the colour gradient relating to the 'Crime Level' for each Crime Type. This is measured against the Cornwall county average

Crime Level: are presented for each area relative to all areas across the county. This allows comparison across each area in Cornwall. The classification method is described above. The data values are categorised into the following bands:

Rate: To show a meaningful comparison, crime levels are displayed as a rate of crime per 1,000 head of population for each area and the county.

Crime Trend: This is simply a symbol / text-based description of the '% Change' described below. As such it compares figures for the last 12 months with those for the same seasonal period for the previous 12 months. We are using 5 descriptive categories to describe the magnitude of the change - the trend. The following classes are used consistently for all crime types based on % Change:
^Significant decrease = < 30% ^Decrease = < 15% -Little change = between +/- 15% ^Increase = >15% ^Significant increase = >30%

Change: Change compares the difference between the current 12 month period (we aggregate crimes for each type across the last 4 quarters) against the previous 12 month period and displays the difference as a percentage (called '% Change') and a count (called 'Actual Change').

So, for example, an 'Actual Change' of -11 for Violent Crimes in the quarter July to September 2008 does not mean that the number of Violent Crimes has fallen by 11 compared with the previous quarter (April to June 2008). It actually means that the number of Violent Crimes has decreased by 11 when you compare the total number of Violent Crimes across the period October 2007 to September 2008 (12 months or 4 quarters of data) with the total number of Violent Crimes in the period October 2006 to September 2007. Aggregating data over a longer period (in this case 4 quarters) leads to a more valid indication of Change or Trend.

It is critical to compare 'like with like' in terms of the same periods of the year as there are regular monthly cycles. In Cornwall crime levels tend to rise significantly every year over summer months.

Crime Types

Recorded Crime: The Home Office Counting Rules provide a national standard for the recording and counting of notifiable offences recorded by police forces in England and Wales (known as ’recorded crime’)... For more information see www.homeoffice.gov.uk/rds/countrules.html.

Police recorded crime statistics provide a good measure of trends in well reported crimes and can be used for local crime pattern comparisons. They do not include crimes that have not been reported to the police or that the police decide not to record.

Police recorded crime statistics will be affected by the rules governing the recording of data, systems in place and operational decisions on the allocation of resources. They cover all ‘notifiable’ offences recorded by the police – ‘notifiable’ means they are passed to the Home Office. This does not mean all criminal offences, as almost all the more minor summary offences are excluded.

Read more about the concerns of the Statistics Commission regarding Recorded Crime in their report: Crime Statistics - User Perspectives

All Crime: This is the total number of all recorded crimes by the police across Cornwall.

The report written by the Statistics Commission (Crime Statistics - User Perspectives) has significant reservations about the validity of using a relatively simple 'All Crime' indicator based on the aggregation of all recorded crimes. They would prefer to see a new indicator developed and universally adopted that applies a heavier weighting to, for example, violent crime.

Criminal Damage: This category includes: Arson, criminal damage to a dwelling, non dwelling or vehicle, other criminal damage, racially aggravated criminal damage, theft or possession with intent to commit criminal damage.

A person who without lawful excuse destroys or damages any property, whether belonging to himself or another person - intending to destroy or damage any property or being reckless as to whether any property would be destroyed or damaged; and intending by destruction to damage to endanger life of another or being reckless as to whether the life of another would be therefore endangered. An offence such as these caused by fire is charged as Arson

Domestic Burglary: This category includes: Burglary in a dwelling and Aggravated burglary in a dwelling. A person is guilty of a burglary if:

He/she enters any building or part of a building as a trespasser and with the intent to commit any such offence of stealing, unlawful damage, grievous bodily harm of a person therein

Theft: This category includes: Profiting from the proceeds of crime, shoplifting, Theft from a person, theft from an ATM or meter, theft in a dwelling other than from an ATM or meter, theft by an employer, theft of mail, dishonest use of electricity, theft of a pedal cycle, Other theft, Handling of stolen goods.

A person is guilty of theft if he/she dishonestly approaches property belonging to another with the intention of permanently depriving the other if it.

Vehicle Crime: This category includes:Theft from a vehicle, theft of a vehicle, aggravated vehicle taking, interfering or tampering with a vehicle.

Violent Crime: This category covers an extensive group of crime types and includes such offences as: Murder, causing death by dangerous or carless driving, wounding, actual or grevous bodily harm, assault, harrasment. These crimes can be split into ‘Most serious violence against the person’ and ‘Other violence against the person’ offences. Also included in this category are Sexual offence and robery.

The ‘most serious’ subgroup comprises violent offences where the injury inflicted or intended is life threatening, and offences resulting in death, regardless of intent.

‘Other violence against the person’ includes offences involving less serious injury. It also includes certain offences that involve no physical injury and some involving serious intent. The category contains crimes where there has been less serious wounding (with or without a weapon) or somebody has been assaulted or there has been a racial/religious attack. Harassment might also be included in this category where someone has been subjected to the fear of violence but no attack has actually taken place.

Most violent crime recorded by the police is low level, in that it involves little or no physical injury to the victim. For a detailed breakdown go to www.homeoffice.gov.uk/rds/countrules.html.

Cornwall Crime Explorer: Background Information