Seventeen percent of youth reported past year beer drinking at Grade 7. Sixteen percent “definitely” or “probably” would drink in the next six months; 23% “probably would not”; 61% “definitely would not.” Partial associations for these outcomes (controlling Grade 6 drinking) are displayed in . Results without this control were nearly identical, and are not displayed. The advertising exposure variables were all significant, positive predictors of Grade 7 beer drinking and drinking intentions. Most of the covariates were also significant, underscoring the need to include them in tests of advertising effects.
Partial associations between candidate predictor variables, beer drinking, and drinking intentions, controlling for Grade 6 beer drinking
In the series of 16 multivariate models (not shown) that separately tested associations of each of the eight advertising variables with a) beer drinking and b) drinking intentions, four of the advertising variables were significant predictors of drinking: TV sports beer ads (β = .28), other TV beer ads (β = .22), radio listening (β = .21), and ownership of promotional items (β = .67; all ps < .05). Exposure to ESPN beer ads just missed significance (β = .22, p = .05). There were significant associations between drinking intentions and: exposure to ads on programs other than sports (β = .26), exposure to magazines (β = .07), and ownership of promotional items (β = .56), all ps < .05.
Complete multivariate models predicting Grade 7 beer drinking are displayed in . We present only the analyses controlling for Grade 6 drinking because the unadjusted results were nearly identical. The joint effect of exposure to ads from all measured sources was significant: F (8, 28) = 8.36, p < .0001, as was the joint test of the three television ad variables alone [F (3, 33) = 3.35, p < .05]. Friends’ approval of drinking was also a predictor, as were low parental monitoring, impulsivity, deviance, and low religiosity.
Multivariate associations between candidate predictor variables, beer drinking, and drinking intentions, controlling for Grade 6 beer drinking
To illustrate the pattern and magnitude of these advertising effects, we used the technique of “recycling.”44 This involves using results of the multivariate tests to calculate the covariate-adjusted probability of the outcome for each participant if he or she had been exposed to “low” levels of the predictor, and then calculating the probability obtained if he or she had been exposed to “high” levels.. One set of predictions was generated based on exposure to all alcohol advertising sources; a second was based on exposure to television advertising for beer. We present results obtained at the 75th percentile of exposure to advertising (high exposure) versus those at the 25th percentile (low exposure) in . As compared to low-exposure youth, the probability of subsequent drinking was 27% higher among youth exposed to the most television ads; the probability of drinking was more than 50% greater among those with the highest advertising exposure from all sources.
Covariate-adjusted predicted probabilities of Grade 7 drinking by level of advertising exposure at Grade 6.
Results of the multivariate models predicting drinking intentions are also displayed in . The joint test of all advertising variables was significant [F (8, 35) = 7.41, p < .0001], as was the joint test of just the television advertising variables [F (3, 35) = 3.91, p < .05]. Covariates predicting drinking intentions were: peer drinking, parent and friend approval of drinking, deviance, impulsivity, low religiosity, and sports activity.
Predicted probabilities for intentions are displayed in . After statistically equating youth on the covariates in our model, the number who intended to drink was 13% greater in the high television ad exposure group, as compared to the low television ad exposure group (top of figure). The percentage intending to drink among those exposed to high levels of alcohol advertising from all sources was 36% greater than that of those with low exposure (bottom of figure). Conversely, both forms of exposure decreased the probability of respondents reporting they would definitely not drink in the coming months by 7 to 16%.
Covariate-adjusted predicted probabilities of intention to drink at Grade 7 by advertising exposure at Grade 6.