Using a comparison group to provide a baseline against which the treatment group findings are assessed requires a careful assessment of just how equivalent the two groups are in their composition. We have explained how cases are allocated to IDVA and non-IDVA days by the Court Listing Staff without information being available to them on any aspect of the cases beyond their likely duration.
To further examine the possibility of systemic factors leading to selection bias, the IPA treatment and comparison groups are presented in Tables 1 and 2 by a range of demographic and case severity factors to allow assessment of whether the two groups are sufficiently equivalent to allow reasonable comparison. Insufficient demographic data were available for FA cases, though where available they indicated patterns similar to the IPA cases.
The data set out in Tables 1 and 2, together with the description of how the Listings Office functions in allocating trial dates, support a conclusion that the allocation of trials was not subject to any detectable selection bias. The biggest difference is in the Table 1 difference in ethnicity of the accused, which is 53% in the comparison group and 31% in the treatment group, but out of 23 comparisons, one difference can be large simply by chance. The overall pattern suggests the findings to be interpreted as if any difference found between the groups could plausibly result from the presence or absence of IDVA support on the day of trial.
Characteristics of the Cases (both IPA and FA)
Overwhelmingly, most trials were for offences of violence (75%, n = 417), a category that comprises a diverse range of seriousness, ranging from assault without injury to serious wounding and threats to kill. Criminal damage was the second most common crime type at 5% (n = 26). Most of the trial offences involved either no injury, minor injury or threats only (95%, n = 531). This is to be expected, because serious injury offences in English law are most likely to be of an offence classification requiring Crown Court rather than Magistrate Court-level scrutiny. ‘Injury’ is most usually interpreted as physical injury, with very few offences referring to psychological injury.
More than half of all cases were assessed by police using the Government-approved DASH risk assessment tool as ‘standard’ risk (no indicators of serious harm or their imminency identified by police) (58%, n = 323). A further 34% (n = 188) were assessed as medium risk (such indicators identified but not imminent) and 6% (n = 31) as high risk (indicators identified and likely to be realised imminently). The focus of non-court IDVA services is entirely on victims assessed as high risk (SafeLives, 2014), so 94% of these cases involve victims who would not have had access to an IDVA service prior to the court trial date. Thus, the effect on a victim of accessing an IDVA service at this Court, or not, is largely free from the potential of contamination by any previous IDVA input.
In terms of the relationship status between the victim and the accused, 73% (n = 410) of the trials were intimate partner abuse, while 21% (n = 115) were familial abuse. Most victims (86%) were female, for whom the most frequent age banding was 30–39 years, while for the 14% male victims, it was 19–29 years. The racial composition of all these victims closely reflected that of the Court services jurisdiction (see Table 1). In the 12 months prior to trial, 17% of all these victims (n = 86) had been a repeat victim of domestic abuse (18% of trials involved a repeat victim, n = 100/559). In the 18 months after their trial, 18% (n = 92) reported repeat domestic abuse: 55% of these repeats (n = 51) reported one incident and 11% more than three. Almost half of these incidents (46%, n = 90) did not meet Home Office guidelines for classification as a crime and were therefore classified as ‘no-crime’.
In the results displayed below, unless otherwise specified, only IPA data are shown, owing to the paucity of data for FA cases.
Criminal Justice Effectiveness
Trial ‘effectiveness’ is a measure of whether a trial went ahead on the scheduled date. Trials are lengthy hearings and consume court time. Listing trials that do not go ahead is inefficient and it unnecessarily delays genuine trials, with the added trauma of unnecessary delay for victims.
Figure 1 shows IPA trials in the treatment group were less likely than those in the comparison group to go ahead on the scheduled date (RR = 0.88, 95% CI 0.81–0.96). In this analysis and all those following, 95% confidence intervals (CI) are provided to show the range of likely true differences, with statistical significance established at 0.05 whenever the CI range does not cross 1 (from a risk ratio above one to a ratio below one).
Figure 2 shows IPA trials in the treatment group were less successful at achieving a conviction than trials in the comparison group. Treatment group trials had a 12% reduction in likelihood of a conviction than the comparison group (RR = 0.88, 95% CI 0.74–1.05) (In this case the difference is not significant, because the risk ratio crosses from below to above 1). Figure 3 illustrates significant and positive findings for IDVA-engaged family abuse cases however, where family abuse IDVA treatment group trials saw a 25% higher likelihood of conviction than the comparison group (RR = 1.25, 95% CI 0.8–1.98).
Count of Repeat Victimisation — Events (Intimate Partner Abuse Only)
Figure 4 shows the difference between the two groups in repeat victimisation and shows the following:
Trials in the IDVA treatment group had a 96% higher risk of being followed by a repeat domestic abuse incident in the 18-month after trial than trials in the no-IDVA comparison group. This difference is both large and statistically significant (RR = 1.96, 95% CI 1.19–3.23).
Compared to repeat incidents prior to the trials, more of the IDVA treatment group cases moved into repeat incident status after the trial than the non-IDVA comparison cases:
Trials in the treatment group had a 110% increase in risk of resulting in a repeat domestic abuse incident after the trial than before. This is statistically significant (RR = 2.1, 95% CI 1.68–2.75).
Trials in the comparison group had a 30% increased risk of resulting in a repeat domestic abuse incident after the trial before. This is statistically significant (RR = 1.3, 95% CI 0.62–2.73).
Severity of Repeat Victimisation (Intimate Partner Abuse Only)
The severity of the repeat victimisation assessed by application of the Cambridge Crime Harm Index (Sherman et al., 2016) is expressed as the mean number of days of imprisonment for each offence. All the trials concern crimes only and to ensure consistency in the calculation, only the crimes are included, but not the no-crime incidents, which do not attract a CCHI score.
Figure 5 shows the mean harm score in the treatment and comparison groups for IPA trials and repeat reports (these scores are identical for victims and events). Treatment group trial victims experienced eight times more harmful repeat victimisation in the 18-month after the trial than the comparison group.
Another way of looking at repeat victimisation severity is to calculate the percentage change in the treatment group repeat victimisation harm score post-trial against that of the treatment group cases at trial. By this interpretation, treatment group victims experienced a mean harm score post-trial 143% more harmful than the case at trial (33 pre-trial compared with 80 post-trial). Furthermore, the corresponding figures for the comparison group were 99 and 10, a drop of 90%.
Each of these analyses indicates that the IPA treatment group victims experience more reported harm post-treatment than the comparison group.