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Road Safety Branch, Roads and Traffic Authority of New South Wales, PO Box 110, Rosebery NSW 2018, Australia
This paper presents results from a telephone questionnaire survey of drivers on the topic of drink-driving conducted in June 1994. A sample of 500 male and 500 female drivers who drink alcohol were interviewed across NSW. The aims of the survey are to assess current drink-driving issues; and to help provide direction for countermeasure development.
The survey examines factors which influence drink-diving decisions; self-reported drink-driving behaviour; and the shift towards "general prevention" of drink-driving. Multivariate analysis is used to develop a typology of drinks. A number of groups are confirmed, which include drivers self-motivated to comply with the laws and drivers currently deterred by countermeasure activity but who hold inappropriate attitudes to maintain compliance.
Substantial success has been achieved in NSW over the last 15 years in dealing with the drink-driving problem, in reduction in crashes and changes in attitudes. The foundation of the success has been the random breath testing (RBT) program. Despite the success and the substantial countermeasure activity which has continued and developed, there remains a substantial drink-driving crash problem, primarily amongst male drivers.
The aims of the current research were to assess the current drink-driving knowledge, attitudes and reported behaviour, and develop a typology of drink-drivers to help in the development of countermeasures.
Interviews were held with a sample of 500 male and 500 female drivers. Subjects were required to be aged between 17 and 69 and have something alcoholic to drink at least once a month. Quotas were set by age, sex and area of NSW to ensure reasonable sample sizes for making comparisons on these variables.
The questionnaire addressed a range of drink-driving issues, including perceptions and attitudes influencing drink-driving, and exposure to random breath testing. Qualitative discussion group research was conducted prior to the survey to help identify issues to be addressed and quantified in the survey. Questions were "pre-tested" to ensure that the questions were being interpreted and answered as intended, by face-to-face interviewing and subsequently interrogating a sample of 30 subjects on sections of the questionnaire.
Interviews were conducted by telephone by Research International Australia. Telephone numbers were selected randomly from a database of listed numbers. A person was randomly selected within each household (the person with the "last birthday") and interviewed if the selection criteria were met.
The unweighted data were used in the analysis and are reported. Younger drinking drivers are over-represented (as a result of the quota sampling) although to some extent this reflects the age distribution of the drink-driving crash problem. The unweighted data also over-represented females, who are less likely to be drivers and much less likely to drink frequently. Statistical differences between men and women are noted in the tables. (Apart from sex, however, weighting did not generally change the results significantly.) Owing to the large number of measures in the study and hence the large number of potential comparisons, statistical tests were conducted with a statistical significance level of a=.001.
Random breath testing (RBT) has almost universal support in NSW (Table 1) with 98% agreeing "RBT should continue". The continuing impact of RBT is also well accepted with 88% agreeing that "RBT continues to help in reducing drink-driving". Only 19% agree that "police should be giving less attention to RBT". Furthermore, only 14% of men and 7% of women agree that "it is unfair to breath test drivers unless they are affected".
Attitudes, Perceptions and Experience of RBT (% of respondents)
|RBT should continue (agree)||97||99||-|
|RBT continues to help reduce drink-driving (agree)||87||88||-|
|Police should give less attention to RBT (agree)||19||19||-|
|It is unfair to test drivers unless affected (agree)||14||7||x|
|Seen police conducting RBT in the last month||47||39||-|
|Seen police conducting RBT in the last 2-6 months||22||21||-|
|Breath tested in about the last year||51||32||x|
|Likely to breath tested in the next two months||43||37||-|
Exposure to RBT is high with 47% of men and 39% of women reporting having seen police conducting RBT in the last month. Men (38%) were more likely than women (22%) to report being tested in the last six months. In fact 35% of women reported never having been tested, compared with 15% of men. Around 40% reported that it was likely they would be tested in the next two months.
Only drivers who drink at least monthly were included in the survey. This group is two-thirds male when weighted to the population. Even within this group, men drink much more frequently: 30% of men and 19% of women drink at least three times a week; half of the women and a quarter of the men report drinking less than weekly.
Men (27%) were more likely than women (13%) to agree that "I can be a bit over .05 and drive ok as long as I am careful" (Table 2). This question represents a measure of the unacceptability of drink-driving, and has shown improvements over the past few years.
Drink-Driving Attitudes and Reported Behaviour (% of respondents)
|I can be a bit over .05 and drive as long as I am careful (agree)||27||13||x|
|Never drink alcohol before driving||24||39||x|
|Not driven when near or a bit over .05 in the last year||42||38||-|
|Driven once or twice near or a bit over .05 in last year||25||21||-|
|Driven near or a bit over .05 more often in the last year||9||2||-|
Women (39%) were more likely than men (24%) to report "never having any alcohol to drink before driving", and less likely (23%) than men (34%) to report "driving when near to or over .05" (Table 2). (This question measures self-judged drink-driving only and does not attempt to identify illegal drink-driving. It is meant to be a broad measure of behaviour.)
Subjects were asked how important were each of a number of factors in their decision about drink-driving when near to or over .05 (Table 3). The two main risk factors - "fear of crashing" and "fear of being caught by RBT" - were rated similarly by men (around 60% saying very important), while women tended to rate crashing as more important (76% vs 60%). The other factors are consequences of being caught or crashing. Among these, "injuring someone else" is the most important for men and women, with "loss of licence" also important for men.
Factors Rated "very important" in Decisions Not to Drive at .05% (% of respondents)
|Factors ( r=risk factor, c=consequence)||Men||Women|
|Injuring someone else (c)||90||95|
|Loss of licence if caught (c)||80||76|
|Injuring yourself (c)||63||74|
|Arrest process if caught (c)||56||75|
|Losing your job if lose licence (c)||69||60|
|Getting caught by RBT (r)||57||60|
|Embarrassment with friends and family (c)||40||54|
|Getting fined if caught (c)||39||53|
A K-means cluster analysis (SPSS, 1992) was conducted to develop a typology of drink-drivers. The analysis was on male subjects, being the major drink-driving crash group.
A principle component analysis (SPSS, 1992) was conducted on a series of attitudes as a first step in reducing the number of variables. Some variables which were loaded on the main factors were combined so as not to give the common "factors" a high weighting in the cluster analysis. Eight attitudinal measures (collapsed to 3-point scales) were selected for the analysis as suitable for determining the typology. A four cluster solution was used (Table 4).
Cluster analysis on attitudes of male drivers (% of respondents)
|(% of sample)||39%||31%||16%||15%|
|Reported drink-driving behaviour|
|- Never drink alcohol before driving||28||22||15||22|
|- Not driven when near to or over .05 in the last year||52||37||42||26|
|- Driven near to or over .05 once/twice in the last year||15||33||28||31|
|- Driven near to or over .05 more often in the last year||5||7||14||21|
|*Drive over .05 if careful (disagree)||98||46||42||27|
|*Difficult to drink less than the group (disagree)||74||29||82||17|
|*RBT helps reduce drink-driving (agree)||95||90||91||61|
|*Police should give less attention to RBT (disagree)||71||37||63||26|
|*Measure of RBT practices as unfair (disagree)||84||29||84||49|
|*Fear of crashing in decisions at .05 (very important)||79||86||17||9|
|- (quite + very important)||97||99||46||36|
|*Fear of RBT in decisions at .05 (very important)||63||74||35||30|
|- (quite + very important)||91||97||73||75|
|*Fear of legal consequences measure (very import.)||43||54||8||5|
|- (quite + very important)||91||94||53||55|
|Fear of losing licence if caught (very important)||89||70||69||82|
|Frequency of drinking (few times a week or more)||19||35||45||35|
|Average number of standard drinks on last occasion||3.8||4.6||5.5||7.1|
|Drove to venue on last occasion||46||47||49||46|
|Drove home on last occasion||38||41||45||22|
The clusters appear to be categorised mainly on two axes: importance of factors in decisions about drink-driving and acceptance of .05 and countermeasures. An examination of the attitudinal profile and reported behaviour indicates interesting differences in risk-taking elements within the clusters.
This group is the most accepting of drink-driving countermeasures and of .05, has the lowest proportion of frequent drinkers, and drank the least on the last drinking occasion. The group is highly motivated to comply with the law, based on importance both of crashing and of being caught, and has the lowest reported drink-driving.
This group reports high motivation to comply with the law. In comparison with Cluster 1, the group has a much lower acceptance of countermeasures and of .05, and reports a much higher level of social pressure not to "drink less than group". This profile suggests an element of potential risk-taking.
This group reports higher levels of agreement with countermeasures, although acceptance of .05 is not as high as in Cluster 1. The group is not as highly motivated to comply with the law (although loss of licence is very important) but in contrast with Clusters 1 and 2 the threat of RBT is rated higher than crashing, suggesting a lower level of self-motivation to comply.
This group consumed the most alcohol on the last drinking occasion and has the highest reported incidence of drink-driving. The group combines lower motivation to comply, lower agreement with countermeasures and the lowest acceptance of .05; and shares with Cluster 3 the pressure not to "drink less than group", and lower fear of crashing. While the group contains the highest risk elements, a much lower proportion drove home on the last occasion.
The survey results show a generally high acceptance of drink-driving countermeasures and strong public opposition to drink-driving in the context of the current laws.
The reported levels of exposure to RBT and perception of RBT have been achieved with an intensive RBT program. The typology of drivers based on drink-driving attitudes demonstrates the continuing role of RBT in deterring drink-driving.
Given the attitudes of the higher risk elements, the potential of the following types of strategies are indicated: implementing targetted enforcement activities to build on the threat of RBT; developing intervention strategies in drinking environments to influence behaviour; and marketing alternatives to drink-driving.
SPSS (1992). SPSS for Windows: professional statistics, release 5, SPSS Inc. Chicago, Ill.