. The Offenders Index (OI) is a database intended to contain all court disposals relating to standard list offences since 1963 in England and Wales and is the standard research tool used for conviction studies.
• The Police National Computer (PNC) is an operational policing database for the UK (excluding Northern Ireland), which contains additional information, particularly on cautions, warnings and dates of offence. It is not suitable for research into criminal histories, as weeding of records takes place periodically. Police records from the period prior to its launch in 1995 are being computerised and integrated into the PNC database.
• The purpose of the present research is to investigate the feasibility of merging PNC records into extracts from the Offenders Index to maximise the information available for research and evaluation of patterns of offending.

Aim of research study
• To assess the quality of the PNC and the Offenders Index data sources
• For selected subgroups of cases, to match OI data with PNC data and to assess rates of matching
• To develop a strategy whereby, for any set of offenders, the two sets of information could be merged into a single data source