Extreme response bias in measuring susceptibility to smoking.

Pierce, Choi, Gilpin, Farkas, and Berry (1998) were the first to claim that they could provide causal evidence that tobacco industry advertising and promotion caused adolescent smoking. This claim continues to significantly influence the theory and conceptualization of how youth react to tobacco marketing. The Pierce et al. (1998) methodology has been used by many researchers to establish the influence of tobacco marketing on adolescent smoking (Goldberg, 2003; NCI, 2006; Sargent, Dalton, & Beach, 2000). Pierce et al. (1998) selected respondents for only the second of their two survey longitudinal study because they chose the extreme-negative response. This choice could be the result of the tendency of some significant number of sample members exhibiting extreme-response bias. The results from an analysis of several questions from the original data used by Pierce et al. (1998) has suggested that there is a significant extreme-response style pattern in the Pierce et al. data. This unaccounted for bias in the responses of their sample was due to the procedure used by Pierce et al. (1998) in the selection of their respondents. The Pierce et al. (1998) sample selection procedure requires more research before the causal link can be claimed.

How well does the index of receptivity to tobacco industry promotion discriminate between smoking and never smoking adolescents.

Tobacco advertising is often named as the culprit that causes children to start smoking (Lancaster & Lancaster, 2003). This belief can partly be attributed to the Index of Receptivity to Tobacco Industry Promotion (IRTIP) developed by Evans, Farkas, Gilpin, Berry, & Pierce (1995). IRTIP was later modified and used by Pierce, Choi, Gilpin, Farkas, & Berry (1998) in a longitudinal study that claimed to have found a causal link between advertising and adolescent cigarette trial. The model is advertised by the American National Cancer Institute (2004) as being able to measure the likelihood of an adolescent starting smoking. Because of Pierce’s causality claim and this endorsement, IRTIP has been widely adopted by tobacco-control researchers. Consequently, the results from IRTIP based surveys have played a central role in influencing tobacco control policy. Based on the logic that a model used to predict the chances of a non-smoker becoming a smoker should be able to distinguish between these two groups, discriminant analysis with dummy coded variables was used to validate IRTIP. The results show that while IRTIP classifies never-smokers well, it grossly misclassifies smokers. This leads to questions about the validity of the model and of studies using IRTIP.