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Security and the Drop in Domestic Burglary
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Security and the Drop in Domestic Burglary
Our next focus was on domestic burglary. This has also dropped steeply and the drop has been sustained, as shown in Figure 10. 3.
Our approach to domestic burglary was broadly similar to that for car theft: ana- lyse successive sweeps of the CSEW to track changes in security levels; assess the SFPs of security devices and combinations of devices; and look at the changing means of entry to households (modus operandi) (Tseloni et al., 2017). Findings again cor- roborated the security hypothesis: levels of most forms of security have increased; modus operandi indicate that falls were disproportionate in methods requiring that security be overcome (as against, for example, walk-in burglaries); and the most effective combinations have tended to increase more than others.
Again, we were limited to what the CSEW covered in the questions asked. The survey was not designed to test the security hypothesis. In particular, we noted that there is a matching inverse trend in the proportion of properties with double glazing
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Domestic burglary with entry
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FIgure 10. 3 Trend in numbers of domestic burglaries with entry CSEW 1981-2016
Source: Crime Survey of England and Wales, Office for National Statistics
and the levels of domestic burglary with entry. Data on double glazing was not obtained from the CSEW but from other sources. We have been able, thus, to note the broad association and the plausibility of a causal relationship (it is more difficult to break into houses with double glazing), but we have been unable to examine it in detail (Farrell et al., 2014).
One unexpected and paradoxical finding that emerged from the analysis of multi- ple sweeps of the CSEW relates to burglar alarms (Tilley et al., 2015). We noted that the SPF for burglar alarms in the later sweeps was less than one. In other words, dwellings with a burglar alarm as their sole security device were at slightly greater risk of burglary than dwellings with no security device at all! We wondered if this occasional observation was spurious – perhaps a function of a sampling error. We therefore devised a marginal SPF (MSPF) that would compare the SPFs of any given combination with and without a burglar alarm. Figure 10. 4 shows our findings, which compare the MSPFs for earlier and later suites of sweeps of the CSEW.
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The overall findings are clear. In the earlier sweeps, the addition of a burglar alarm tended to reduce risk, in some cases substantially. In later sweeps, this effect was reversed. The addition of a burglar alarm increased risk. This suggests that security devices may not unequivocally and under all circumstances reduce crime risk.
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FIgure 10. 4 Marginal SPFs for burglar alarms, burglary with entry
Source: Tilley et al. (2015).
TaBle 10. 2 Quantitative data signatures consistent with security having reduced domestic burglary
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· A steep decline in households without security coincided with burglary’s decline
· Variation in the effectiveness of different security devices are consistent with their preventive mechanisms
· Preventive effects are much stronger when multiple security devices are in place
· The drop was mainly a decline in forced entry through doors and windows, consistent with improved security
· Unforced entries (push-pasts, keys used, deception) increased when forced entries and all burglary decreased, consistent with partial short-term displacement as a result of effective security
· Door-forcing at the rear of properties fell first and fastest, consistent with security at the previously most vulnerable entry point
· There was a disproportionate decline in adolescent crime, consistent with novices being more easily deterred by improved security
· The rate of attempted burglary fell later than completed burglary, consistent with offenders continuing to try before quitting in the face of improved security
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Burglary fell slightly faster among more affluent households, consistent with more rapid upgrading
We proposed various conjectures, but were unable to test any of them. We suspect that, as burglary has declined, the pool of burglars has become, on average, slightly older and more experienced, and these offenders are unlikely to be deterred by an alarm because they know the chances of the police arriving quickly are small.
The core set of quantitative data signatures that we have identified relating to household burglary and the role of security are summarized in Table 10. 2. All of the signatures are consistent with security being the cause of the decline in burglary.
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