Dear Max

Statistics on Rape and Sexual Offences

At the Office for Statistics Regulation, our role is to investigate any concerns about the quality, good practice, and comprehensiveness of official statistics. While the Crown Prosecution Service (CPS) is not an official statistics producer, it publishes quarterly bulletins of data tables and summaries of main trends as part of its ongoing commitment to transparency on prosecution performance.

We have been contacted about CPS’s statistics on Rape and Sexual Offences in its quarterly data summaries. The complainant highlighted three issues regarding how the data are collected, presented and explained by CPS.

The first issue is that it is not clear in the main section of the bulletin exactly what is being counted when it refers to rape cases, with this only being explained towards the end of the publication. The caveats and limitations of the data are not prominent which does not support appropriate use of the data. To enhance clarity, CPS could include a definition above the table that breaks down the rape data and outcomes, that explains that the figures are referring to rape flagged cases.

The second issue is that CPS is publishing management information on conviction rates that is different from the conviction rates data published by the Ministry of Justice (MoJ). The discrepancy is due to a difference in methodologies used. MoJ counts the number of prosecutions by offence/principal offence, whereas CPS counts the number cases with a rape flag. To support understanding, we would encourage CPS to make the statement that explains that these data are sourced from management information, and signposts readers to official statistics on criminal justice outcomes published by MoJ and the Home Office, more prominent in the quarterly releases.

The third issue raised with us is that CPS’s case flagging system may lead to inflated figures for the number or charges and conviction data for rape. This is because where a defendant is charged with rape and sexual assault, but then the rape charges are dropped or the defendant is only convicted of sexual assault, they are still included in the charges and conviction data for rape.

Analysts in CPS informed us that the system was not designed to capture this information but recognised it was a limitation of the data. The purpose of the flagging system is to track the whole lifecycle of cases so that the victim in cases such as rape or other flagged cases are fully supported throughout. This methodological limitation is crucial for interpreting the end data and must be made clearer to users, through a prominent caveat alongside the data.

It is never our aim to inhibit transparency and we welcome the fact that CPS is putting these data into the public domain to inform public debate. However, the distinction between official statistics and other data may seem artificial to many users of these data. Releasing data without sufficient context and clarity may limit the extent to which they can usefully inform public debate and does not meet our expectations for intelligent transparency.

We therefore strongly recommend that CPS takes steps to voluntarily apply the Code of Practice for Statistics. This will demonstrate to users that CPS seek to commit itself to the highest principles and practices of trustworthiness, quality and value embedded in the Code.


Yours sincerely


Ed Humpherson
Director General for Regulation