The effectiveness of burglary security devices

The Crime Survey for England and Wales (CSEW) estimates that 2.1 per cent of households in England and Wales were burgled in 2012/2013 and experienced 694 000 burglaries (Office for National Statistics, 2013). The impact of burglary upon victims is significant, and includes considerable psychological costs in addition to the financial costs of replacements and repairs. In response, many households have adopted security measures of various types. Victim Support and Crime Prevention Officers routinely advise victims of crime to improve aspects of their household security (Spackman, 2000). However, unlike household insulation and other similar ‘green’ interventions there is, by and large, no government support for the installation of security devices within households in the United Kingdom and so security is generally left to the discretion of the individual. Poorer households in society are evidently less able to afford the installation of physical security measures. Where target hardening is provided to householders as part of specific crime reduction campaigns, this is often limited in scope because of funding availability, and may be provided to those who are perceived to be more vulnerable (for example, the elderly) regardless of whether or not they are shown to be at greater risk (Grove et al, 2012). Households in the rental sector also require the cooperation of landlords to make changes to their residence, which may not always be forthcoming. In the United Kingdom, fire alarms are mandated in rental properties (Gov.uk, 2013). There is no equivalent requirement for household security, although a minimum security standard for new buildings is currently under consideration (DCLG, 2014).

Household anti-burglary security comes in a variety of forms, and there is mixed evidence about their effectiveness: it appears that some devices are more effective in thwarting burglaries than others. Homes with no or low-level security have 7 times and 75 per cent, respectively, more burglaries than homes with high-level security (Pease and Gill, 2011).¹ Van Dijk (2008, p. 55) suggests that routine investment in security devices can result in a higher proportion of ‘failed burglaries’. The use of preventive security measures is increasing in most countries, with the highest levels in developed countries (Van Kesteren et al, 2000). This correlates with a higher proportion of attempted, rather than successful, burglaries in these countries (ibid.). In a natural experiment whereby newly built homes were required to have burglary security in the Netherlands, the burglary rate fell in areas with new housing but without displacement to areas with older less-protected houses (Vollaard and van Ours, 2011). It was concluded that by 2010 the national burglary rate in the Netherlands was 5 per cent lower than it would have been otherwise.

Nee and Meenaghan (2006) interviewed 50 offenders, finding burglars preferred properties with relative wealth and physical cues that offered them cover, access and getaway routes. They write that: ‘Interestingly, security cues were mentioned least frequently … In any case, all participants felt security features were rarely enough to deter them, due to a lack of vigilance in locking up on the part of homeowners’ (Nee and Meenaghan, 2006, p. 942). This fits with earlier offender interviews that suggested that, in isolation, common household security measures may have a limited deterrent effect (Reppetto, 1974). However, Cromwell and Olson (2009) found some practical burglary prevention measures, such as target hardening and visibility improvements, to have a deterrent effect, while a study of four police divisions in Kent concluded that ‘the security of victim households is no lower than the average’ (Winchester and Jackson, 1982, p. 20).

Households with less-than-basic security were found to experience 6 times more burglaries than those with basic security, and 10 times more than those with enhanced (Flatley et al, 2010, p. 2). Households with no security were also found to be at greater risk than those with basic or enhanced security (Tilley, 2009; Flatley et al, 2010). A further study found that households with an income less than £5000 and in possession of enhanced security had 25 times lower odds of burglary with entry than same-income households with no security. In contrast, basic security conferred effectively no protection for £20 000–£29 999 income households in 1997 (Tilley et al, 2011). With the exception of this categorisation, past research on the relative effectiveness of security devices does not, to our knowledge, examine the effectiveness of each separate device or the various permutations of their combination. For this reason it seems that the evidence on the effectiveness of anti-burglary security devices is somewhat mixed.

It is in this context that the present study aims to shed further light on this important issue and to separate the effects of devices used individually and in combination. In particular, it aims to answer the following question: What are the preventive effects, if any, of individual and combined burglary security devices against domestic burglary with entry and attempted burglary in England and Wales?

The present study is broadly consistent with the criminological theory of environmental criminology. A term coined by Jeffrey (1971), environmental criminology encompasses the rational choice and routine activity perspectives. In the present context, security devices tend to make the target – the household – less suitable for victimisation (target suitability being a cornerstone of routine activity theory (Cohen and Felson, 1979). The way in which the target becomes less suitable varies with type of security device, with each either increasing the actual or perceived risk or effort involved. This is consistent with situational crime prevention which is a key operational component of environmental criminology (see Cornish and Clarke, 2003 for the definitive statement of the 25 techniques of situational crime prevention). Each of the preventive mechanisms is intended to tip essentially ‘rational’ offenders away from the decision to commit crime.

The structure of this article is as follows. The next section details the data and methodology used to identify the effectiveness of anti-burglary security devices. The preventive effects of individual devices and selected configurations are then detailed and the study concludes with a summary of the findings and a discussion of their policy implications.

With respect to terminology, we recognise that some security devices require an action on the part of the owner to be activated. For this reason, the term security availability that denotes whether certain burglary devices are present in the home rather than security use is used herein. This recognises the fact that whether devices are in use is a different research question which is not within the scope of the present study but might, at least in part, be addressed in future research that focuses on modus operandi. For brevity, ‘burglary with entry’ is sometimes referred to as burglary, and attempted burglary as attempt(s).

This study analyses the CSEW (formerly the British Crime Survey, BCS) data from 2008/2009 to 2011/2012. The CSEW is a national (for England and Wales) victimisation survey, currently run by the Office for National Statistics. CSEW sweeps were undertaken on an occasional basis between 1982 and 1992 and biennially between 1992 and 2000. Since 2001/2002 it has used an annual rotating sample of roughly 40 000 respondents. The survey uses a multistage stratified sample, which is representative of the adult (16 years or older) population living in private accommodation in England and Wales. For a brief history and details of the methodology, questionnaire modules and items, and topics covered in the CSEW, see Hough and Maxfield (2007) and the various CSEW Technical Reports (www.ons.gov.uk/ons/taxonomy/index.html?nscl=Crime+in+England+and+Wales, accessed 25 September 2013). Response rates have been consistently high varying between 73 and 81 per cent (Jansson, 2007).

For economy of space the enlarged capital bold letters in the previous list will denote the respective security device in the remainder of the article.² Information about the availability of the same list of security devices at the time of the incident is solicited (via the Victim form Module) from respondents whose household was burgled. However, not all burglary victims were asked about their home security. This is because respondents complete a maximum of six Victim Forms – three using a long questionnaire and three using a shortened version. As questions about home security availability are included only in the long Victim Forms, data on home security at the time of the burglary are not available for the minority of respondents who reported at least three unconnected crime incidents of higher seriousness than burglary (according to standard offence classification – see Hales et al, 2000) during the year preceding the interview.³ This means that information about the anti-burglary security adopted by the survey’s most victimised respondents is not available.

The unit of analysis here is the household. For this reason when a victim reported repeated burglary incidents via more than one long Victim Form, their home security availability at the time of the first burglary during the survey’s reference period has been retained for analysis. In the 2008/2009–2011/2012 CSEW data, 2.66 per cent of burglaries with entry and 1.65 per cent of attempted burglaries with available security information were repeats. After an initial burglary the use of external lights and burglar alarms doubles while acquiring window locks increases by 50 per cent among burglary victims in England and Wales (Budd, 1999). Similarly in the United States an additional burglary for every 1000 people increases the demand for burglary alarms by 3 per cent (Philipson and Posner, 1996). Victims’ response to a first burglary and whether this alters subsequent burglary risk, while acknowledged as of great interest, is outside the scope of the present study.

For the purposes of this analysis the Crime Prevention Module C sample represents the exposed population of households or the homes fleet in England and Wales. Burglary victims, as identified by the CSEW long Victim Forms, reflect the targeted households of this analysis. A minority of cases where a respondent experienced both an attempt and a burglary with entry are, however, excluded.⁴ To increase the potential number of homes with any possible security configuration from the above list of devices the four sweeps, that is, 2008/2009, 2009/2010, 2010/2011 and 2011/2012, of the CSEW data have been merged in a single data set. Together these record crimes that occurred to respondents from April 2007 to March 2012.

This work uses the Security Impact Assessment Tool (SIAT) methodology developed and described by Farrell et al (2011) in their study of the effectiveness of car security devices. Here the SIAT methodology compares the likelihood of burglary for populations without security, with a particular security device or combination of devices to the overall likelihood of burglary. This comparison results in odds ratios. Contrasting the odds ratios given the availability of a security device or combination of devices with respect to no security identifies the amount of protection conferred relative to no security. The resulting metric is termed the Security Protection Factor (SPF). The coincidence between this abbreviation and that denoting Sunscreen Protection Factor is serendipitous because ‘in both cases the SPF states the multiples of additional exposure time, relative to the absence of protection, beyond which the average owner is burned’ (Farrell et al, 2011, p. 23). The underlying principle of the SIAT is simple. If no protection is conferred, the distribution of security devices would be the same between burgled households and all households in the population, the homes fleet. Specific aspects of the methodology will be clarified as the results are described.

The extent of the protection conferred by individual anti-burglary devices and selected combinations is discussed in this section. Table 2 presents the information that enables calculating the SPFs. The SPFs for individual devices are shown in Figure 1 and those for combinations in Figures 2 and 3 and Table 3 later in this section. An indication of the statistical significance of the odds ratios is given in both Tables 2 and 3.⁶ Burglary security devices in Table 2 and their configurations in both tables are listed in descending order of sample size in the 2008/2009–2011/2012 CSEW to allow the extent of their use in England and Wales better to be appreciated.

Table 2

Sample sizes and odds ratio of burglary with entry and attempted burglary across individual security devices and their configurations (2008/2009–2011/2012 CSEW)

Security devices a	Number of respondents			Odds ratio
	All households	Victims of		Burglary	Attempt
		Burglary	Attempt
No security	1835	821	286	7.46**	4.30**
WD	5381	192	111	0.59**	0.57**
EWD	3307	43	37	0.22**	0.31**
WSD	2743	38	56	0.23**	0.56**
EWBD	1953	53	40	0.45**	0.57**
W	1765	120	69	1.13	1.08
EWSD	1687	24	15	0.24**	0.25**
EIWBD	1589	24	23	0.25**	0.40**
EIWD	1537	14	11	0.15**	0.20**
WBD	1455	73	39	0.84	0.74
IWD	961	26	6	0.45**	0.17**
EIWSBD	931	3	13	0.05**	0.39**
D	905	145	105	2.67**	3.20**
EWSBD	870	12	15	0.23**	0.48**
EIWSD	824	13	4	0.26**	0.13**
WSBD	709	17	13	0.40**	0.51*
WS	678	24	26	0.59**	1.06
EW	675	17	17	0.42**	0.69
IWBD	530	13	8	0.41**	0.42*
IWSD	515	10	7	0.32**	0.38**
SD	463	27	23	0.97	1.37
S	321	70	38	3.63**	3.27**
IWSBD	314	6	9	0.32**	0.79
ED	313	13	18	0.69	1.59
WB	272	26	13	1.59*	1.32
EWS	253	8	9	0.53	0.98
E	242	36	19	2.48**	2.17**
EWB	229	10	14	0.73	1.69
B	212	106	52	8.33**	6.77**
EIW	177	6	2	0.56	0.31
ESD	171	5	3	0.49	0.48
CWD	161	3	2	0.31*	0.34
CEIWBD	152	2	4	0.22*	0.73
IW	149	8	3	0.89	0.56
CEWD	145	0	7	—	1.33
CEWBD	145	2	6	0.23*	1.14
BD	136	31	21	3.80**	4.26**
CWSD	116	1	1	0.14*	0.24
Don’t know	114	44	61	6.43**	14.76**
EIWB	103	4	7	0.65	1.88
WSB	93	3	6	0.54	1.78
EBD	90	6	6	1.11	1.84
ID	86	4	6	0.78	1.93
EWSB	85	3	4	0.59	1.30
CEWSBD	82	0	2	—	0.67
EID	82	4	2	0.81	0.67
ES	71	7	6	1.64	2.33*
EIWS	69	0	3	—	1.20
CW	65	2	1	0.51	0.42
CWBD	64	0	2	—	0.86
IWS	57	5	1	1.46	0.48
C	57	16	9	4.68**	4.36**
IWB	56	4	2	1.19	0.99
Other configurationsb	1171	101	93
Including: I	47	6	5	2.13	2.94*
Y	34	11	9	5.39**	7.30**
G	21	7	2	5.56**	2.63
Total	37 416	2245	1356

^aThe configurations ‘CEWSD’, ‘CEIWD’, and of all 7 security devices, ‘B, D, S, W, I, E and C’, were reported by 81, 72 and 97 respondents, respectively but no burglary victims in the 2008/2009–2011/2012 CSEW merged data set. Therefore they are omitted from Table 2.

^b‘Other configurations’ refers to all the remaining ones with each reported by less than 50 respondents. For this reason they are not examined further here except for the individual devices that are included within this category.

*0.05>P⩾0.01; **P⩽0.01.

Notes: Abbreviations: B=Burglar alarm; C=CCTV; Y=Dummy Alarm; D=Door double or deadlocks; E=External lights on a timer or sensor switch; I=Indoor lights on a timer or sensor switch; S=Security chains; G=Window bars or grilles; W=Window locks.

Table 3

SPFs and NIEs of burglary with entry and attempted burglary across security devices configurations (2008/2009–2011/2012 CSEW)

Security devices	Burglary with entry		Attempted burglary
	SPF	NIE	SPF	NIE
WD	12.54**	3.17	7.56**	2.23
EWD	34.41**	22.03	13.93**	6.62
WSD	32.30**	20.87	7.63**	0.99
EWBD	16.49**	3.21	7.61**	−0.34
EWSD	31.45**	17.02	17.53**	8.90
EIWBD	29.62**	12.84	10.77**	1.35
EIWD	49.12**	33.23	21.78**	13.00
WBD	8.92	−1.35	5.81	−0.15
IWD	16.54**	3.66	24.96**	18.17
EIWSBD	138.85**	120.01	11.16**	0.43
EWSBD	32.44**	17.11	9.04**	−0.23
EIWSD	28.36**	10.42	32.11**	22.01
WSBD	18.66**	6.34	8.50*	1.22
WS	12.64**	4.01	4.06	−1.24
EW	17.76**	8.18	6.19	0.22
IWBD	18.24**	4.47	10.33*	2.89
IWSD	23.04**	8.11	11.47**	3.35
SD	7.67	2.83	3.14	0.48
IWSBD	23.41**	7.59	5.44	−3.31
ED	10.77	4.97	0.69	−0.62
WB	4.68*	−2.79	3.26	−1.36
EWS	14.15	2.51	4.38	−2.91
EWB	10.25	−0.24	2.55	−4.06
EIW	13.20	0.11	13.79	6.36
ESD	15.30	7.45	8.88	4.24
CWD	24.01*	13.04	12.55	6.23
CEIWBD	34.00*	15.63	5.92	−4.48
IW	8.33	7.74	7.74	2.29
CEWD	—	—	3.23	−5.07
CEWBD	32.44*	17.57	3.77	−5.17
BD	1.96**	−1.72	1.01**	−0.97
CWSD	51.90*	38.88	18.08	10.45
EIWB	11.52	−2.47	2.29	−5.78
WSB	13.87	4.34	2.42	−3.52
EBD	6.71	0.02	2.34	−1.63
ID	9.62	3.32	2.23	−0.57
EWSB	12.68	0.14	3.31	−4.61
CEWSBD	—	—	6.39	−3.86
EID	9.17	−0.13	6.39	1.60
ES	4.54	−0.52	1.84*	−1.46
EIWS	—	—	3.58	−5.17
CW	14.54	6.37	10.13	5.16
CWBD	—	—	4.99	−1.97
IWS	5.10	−7.04	8.88	2.12
IWB	6.26	−4.72	4.36	−1.72

*0.05>P⩾0.01; **P⩽0.01.

Abbreviations: B=Burglar alarm; C=CCTV; D=Door double or deadlocks; E=External lights on a timer or sensor switch; I=Indoor lights on a timer or sensor switch; S=Security chains; W=Window locks.

Notes: Results are given in descending order of sample size that reported each configuration; configurations not reported by victims at the time of first burglary cannot produce SPFs.

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The first three columns of Table 2 present the samples sizes for all households in the sample (hereafter ‘all households’) and for victims of burglary with entry and of attempted burglary. Recall that only security configurations with more than 50 households in the sample are shown. The odds ratios that are given in the last two columns of Table 2 are calculated as follows: The bottom row shows that there were 37 416 households in the sample, of which 2245 experienced burglary and 1356 experienced attempted burglary. The first row of the table shows that 1835 of all 37 416 households (4.9 per cent) reported no security devices. However, 821 of 2245 burgled households (36.6 per cent) reported no security, as did 286 of 1356 (21.1 per cent) of household that experienced attempted burglary. The odds ratios compare the percentage with respect to the two crime types to that for all households. Therefore for households with no security, the odds ratio is 7.46 (calculated as 36.6/4.9) and for attempts it is 4.30 (calculated as 21.1/4.9). The superscript notation shows that these odds ratios are highly statistically significant. In a similar way, the odds ratios of different security configurations can be calculated. However, not all configurations have significant odds ratios. In total, 31 individual devices and configurations show odds ratios that are statistically significant for either type of burglary.

The (multiplicative) difference of odds ratios between any individual device or configuration and no security gives its SPF value. These are shown in the graphs of this section and the second and fourth columns of Table 3 with an indication of their statistical significance. They are calculated as follows: In the second row of figures of Table 2, households with window and door locks have an odds ratio with respect to burglary with entry of 0.59, which is 12.54 (7.46/0.59) times lower than no security. This SPF implies that window and door locks confer 12 times higher protection against burglary with entry than no security. Another way of expressing this is that window and door locks reduce the odds ratio of burglary with entry down to one-twelfth compared with no security. This is considerable compared with previous evidence on car security SPFs that did not exceed 25 (Farrell et al, 2011). It appears, however, modest in relation to other burglary security configurations as will be seen in the following paragraphs. The discussion here uses both interpretations interchangeably.

The SPFs of the individual devices and configurations with at least one statistically significant odds ratios from Table 2, as mentioned, are shown across three graphs, Figures 1, 2, 3. They are listed in descending order of the SPFs against burglary with entry values that is in general more responsive to security than attempted burglary as found in previous research (Van Kesteren et al, 2000). An SPF of 1 implies that the odds ratios of no security and the examined device or configuration are equal and therefore the latter confers no protection. SPFs lower than 1 imply that the respective device or configuration is counter-productive: the odds of burglary are actually lower without any security than the device examined. Therefore the following discussion and related graphs of SPFs use 1 (rather than 0) as baseline (the value of the y-axis at which the x-axis intersects) which best reflects the protection conferred by each burglary device configuration.

This study was motivated by mounting evidence that security improvements have played a significant role in the unprecedented long-term decline in volume crime generally, and household burglary in particular, in many industrialised countries (Van Dijk et al, 2012).This is, to our knowledge, the first work to examine the protective effects of all individual burglary security devices for which data are available in the CSEW and their possible configurations. Previous research on burglary security examined wide groups or the presence of a device while ignoring any complementary or combinatory effects produced by the co-presence of one or more other device. This work complements the previous literature, by distinguishing the individual protection effects across a large number of devices and their combinations. In addition, the SIAT methodology offers a novel approach to examining the specific effects of different combinations of security devices, both individually and in combination. Longitudinal analysis using the SIAT methodology may be a possibility for future research.

What advice should be given to householders themselves or to those, such as landlords or crime reduction partnerships, attempting to reduce the burglary risks to vulnerable third parties? From a strictly practical perspective, the research reported here suggests if only one security device is installed then fitting external lights on a sensor (E) seems to provide greatest protection against any burglary. If a further device is included, adding window locks to external lights (EW) is suggested in relation to burglary with entry. The Home Office defined basic security, that is, window and door locks (WD), produces second best results against burglary with entry but confers additional protection against attempted burglary. Window and door locks together with external lights or security chains (EWD or WSD) seem the ultimate choice for balancing out number of devices and protection effectiveness: they confer more security than most combinations of four or more devices. Indeed these combinations of just three out of the seven examined devices confer, respectively, the fourth and eighth highest protection effect against burglary with entry among all 31 significant combinations (see Figures 2 and 3 and Table 3). If more devices can be afforded, however, the highest total protection (ignoring the outlier effect of six devices mentioned in the previous section) can be gained by CCTV, window and door locks and security chains (CWSD) or lights and locks (EIWD) that is the cheapest and safer option given the high cost of CCTV and potential fire hazard posed by security chains. From a narrow viewpoint of burglary security, households, landlords and crime and safety partnerships should not even contemplate installing five devices since such configurations are less effective against burglary with entry than the above triplets and quadruplets.⁷ Therefore there are economies of scale in the number of security devices installed to prevent burglary with diminishing returns after two. The protective value added by a second or third device is up to six – or two-fold than a single device or a pair, respectively. In some instances adding a fourth or fifth device reduces the overall effectiveness of the combination resulting thus in dis-economies of scale. Forthcoming changes to security standards for housing should take this into account.

In terms of cost-effectiveness, further research into the cost of security relative to the cost of burglary is required. A best guess, based simply on the number of devices and impact, would be that there is preliminary prima facie evidence that window and door locks together with external lights or security chains may be the most cost effective. However, additional variables such as level of disposable income and the likely loss from a burglary is likely to weigh in householder’s security decision making, and in that context the present analysis should be viewed as preliminary. ‘One size fits all’ security is less effective than bespoke security that accounts for group composition and context (Pease and Gill, 2011). The present analysis forms the first part of a wider research project on ‘Which Burglary Security Devices Work for Whom and in What Context?’ Future work will seek to qualify the findings reported here for different types of houses, households and areas. Complementing such secondary data analyses findings with burglars’ accounts on how the security combinations examined here may discourage them from breaking in would fully answer any questions the current findings created.