According to the article published by The Police Foundation, important changes have taken place in data recorded by the police forces of England and Wales and provided by the National Criminal Data System, along with an added difficulty when such data is compared with those pertaining to the Crime Survey.
In April 2002 new criteria were defined in order to gather data on behalf of police officers at the National Crime Recording Standard (NCRS), which aimed to promote an accurate collecting of police records in England and Wales and which has now led to an increase in crime data in this territory.
In the United Kingdom, specifically in the territory where the British Home has competence (Home Office), England and Wales, the Crime Survey is carried out (CSEW), which, along with data pertaining to police records, are the main instruments used to analyse crime.
Comparing the data from the two systems of analysis has so far been one of the main studies and sources of analysis of crime. In spite of this, the viability of comparing police records and crime surveys is now being questioned.
According to the opinion of several analysts, police records provide data about the population as a whole and, on the other hand, the survey gives data about the population from the age of 16, as a specific study is done for the population including those aged between 10 and 15. This group seems to be relevant for police records.
Police records calculates whatever is known with the development of police activity. On the other hand, the survey provides data about the population as a whole but does not extend to business or people who do not live at home, such as university students, members of the armed forces or people who reside in caravans. This all leads to differing trends where the survey and police records are concerned.
The number of incidents, represented by ratios, are historically higher in the Survey than in police records, with the non-reporting of some incidents being offered as an explanation for this. However, police-recorded incidents have now been increasing to the extent that, in 2013-2014, there are 12 incidents in police records for every 10 provided by the Crime Survey.
One explanation could be that some types of crime have been under-represented in police records for years. For example, crimes against people have increased significantly over recent years.
The second is that most crimes are on the increase according to police records, which causes these changes in records, an impact felt throughout the territory.
The third factor is that studying violence continues to be particularly difficult because of the credibility of police data and the Crime Survey, particularly when we want to make comparisons.
This situation is not due to the fact that one system is better than the other when knowing the crimes that have taken place in England and Wales, as the types of crime in the Crime Survey and Police records are not completely comparable. It seems that the Survey is not affected by changes in records and, for the moment, has been more consistent when visualising trends.