TABLE 4.

Multivariate Negative Binomial Associations Between Ad Incidence and Audience Age, by Percentage of Underage Viewers (≤30%, >30%), 2001–2006

	Beer		Spirits		Alcopops		Wine
	≤ 30%, IRR (95% CI)	> 30%, IRR (95% CI)	≤ 30%, IRR (95% CI)	> 30%, IRR (95% CI)	≤ 30%, IRR (95% CI)	> 30%, IRR (95% CI)	≤ 30%, IRR (95% CI)	> 30%, IRR (95% CI)
% of audience aged
2–11 y	0.94*** (0.93, 0.96)	0.90*** (0.87, 0.92)	0.92*** (0.89, 0.95)	0.87*** (0.82, 0.92)	1.04 (1.00, 1.08)	0.78*** (0.72, 0.85)	0.80*** (0.77, 0.83)	0.92** (0.88, 0.97)
12–20 y	1.07*** (1.06, 1.09)	0.83*** (0.81, 0.85)	1.15*** (1.11, 1.18)	0.84*** (0.78, 0.90)	1.22*** (1.18, 1.26)	0.82*** (0.79, 0.86)	0.92*** (0.89, 0.94)	0.90*** (0.85, 0.95)
21–24 y	1.10*** (1.07, 1.13)	1.16*** (1.07, 1.26)	1.09** (1.04, 1.14)	1.81*** (1.50, 2.19)	1.38*** (1.30, 1.46)	1.09 (0.92, 1.31)	1.12*** (1.06, 1.18)	1.10 (0.94, 1.28)
≥25 y (Ref)	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00

Note. CI = confidence interval; IRR = incidence rate ratio. Multivariate regressions also included indicator variables for all 13 dayparts and all 167 alcohol brands (not shown). The ad IRR is the amount by which ad incidence per viewer-hour is multiplied for each 1-unit increase in a given predictor, with control for all other predictors. For example, a 1-point increase in percent of adolescent viewership corresponds with a 22% greater increase in the incidence of alcopop ads per viewer-hour than does a 1-point increase in percent of older adult viewership. For ease of interpretation, we do not report the interaction terms but instead translate them into separate associations for time slots with a percentage of underage viewers less than or equal to 30% or more than 30%.

*P < .05; **P < .01; ***P < .001.