Deliverable D 1.3 RESULTS OF META-ANALYSIS ... - cast-eu.org

Campaigns and awareness raising strategies in traffic safety — Deliverable D-1.17. EFFECTS OF CAMPAIGNS FROM ANALYSIS OF CASTDATABASEThe CAST database contains data describing a sample of campaignevaluation studies. This chapter describes how the studies were retrieved(section 7.1) and gives a descriptive analysis of the sample of studies (section7.2). An example is given to show how the sample was ‘meta-analysed’(section 7.3) before the overall effects generated by meta-analysis aresummarised (section 7.4). Bivariate analyses of factors potentially associatedwith variation in the overall effect of campaigns are given (section 7.5), beforeoverall effects and associated influences exclusively for those campaigns inthe sample using mass-media are provided (sections 7.6 and 7.7).7.1 STUDY RETRIEVAL AND PROCESSING7.1.1 STUDY RETRIEVALStudies describing the evaluation of a road safety campaign carried out overthe last 40 years were considered. The definition of a road safety campaignused was quite broad, as described earlier in this deliverable. Each study wasscanned for any reported campaign effects (i.e. the change in an outcomemeasure taken either before-and-during or before-and-after the campaign). Asurprising number of studies only reported measures taken during or after thecampaign. These were omitted.The outcome measure of ultimate interest to CAST is accident counts, but wewere also interested in the effects of campaigns on other road user behaviour,such as the percentage of car occupants wearing seatbelts or driversspeeding.A total of 221 studies containing suitable campaign effects were identified. Ofthese studies, 44 were generated by the systematic selection and summary ofroad safety campaigns by CAST partners. This was achieved by invitingpartner representatives to fill in a form for each campaign evaluation theywere aware of from their respective home countries. The form was designedto capture each of the database variables (see 7.1.2). A further 144 studieswere included as the result of re-assessment of road safety campaignevaluations used in previous meta-analyses (Delhomme et al, 1999; Vaa et al,2004; Elliott, 1993; and Elvik and Vaa, 2004). A literature search for morerecent road safety campaign evaluations, performed using accessible andrelevant databases, resulted in the retrieval of a further 33 studies.Of these 221 studies, 173 studied contained information that could be used inthe final meta-analysis. 22 .22 For example, speed measures reported simply as kph or mph in the absence of standarddeviations or number of people surveyed could not be used. Studies reporting percentageswithout n numbers could not be used. Other studies contained unusual outcome measures ofwhich there were not a sufficient number for meta-analysis.54