Thursday, March 20, 2014

Exactly 44% of Kids Who Start Smoking Do So Because of Smoking in Movies

Not that our science allows us to be precise to the percentage point, but the American Legacy Foundation has publicly claimed that exactly 44% of kids who start smoking do so because of having seen smoking in the movies.

The claim is made in a press release entitled "44 Percent of Adolescents Who Start Smoking Do So Because Of Smoking Images They Have Seen In The Movies."

According to the press release: "As viewers around the world prepare to tune in for Sunday's 86th annual Academy Awards honoring achievements in the film industry, the public health community is drawing attention to new data concluding that by eliminating tobacco imagery in youth-rated movies, youth smoking rates could decline by an estimated 18 percent. Incidents of smoking in youth-rated films have doubled between 2010 and 2012, returning to levels of a decade ago. In fact, according to Thumbs Up! Thumbs Down! two of the three PG-13 movies (Captain Phillips, Philomena) that are nominated for Best Picture this year include smoking. Large-scale studies have demonstrated that movies with smoking cause youth to start smoking, and this rebound represents a set-back for national youth tobacco prevention goals. According to research funded by Legacy, in 2013 youth-rated movies delivered an estimated 14.8 billion tobacco impressions to theater audiences, a 169 percent increase from 2010."

The Rest of the Story

The major problem with this claim is that exposure to smoking in movies is likely to represent a proxy measure for a wider constellation of media-related exposures to smoking that likely all contribute to the smoking initiation process. These include magazine advertising, outdoor advertising (especially on the exterior of stores and point-of-sale advertising within stores), exposure to smoking on television, in music videos, video games, the internet, etc.

The studies upon which the 44% figure is derived did not produce a comprehensive picture of each youth's exposure to smoking in all media and then isolate the impact of smoking in movies. In fact, these studies simply compared smoking initiation between youth with differing levels of exposure to smoking in movies.

Therefore, I don't think it is valid to isolate the specific impact of exposure to smoking in movies and claim that this exposure alone is the cause of youth smoking in these 44% of youth smoking cases. It is likely that a much wider array of exposures is contributing to the initiation process. Exposure to smoking in movies may certainly be one of them, but it is not the only one, and I do not believe that from the underlying studies, which didn't measure any of these other exposures, one can tease out the smoking in movies and claim that it is the precise (and sufficient) cause of the observed smoking behavior.

Why is this important? After all, couldn't one argue that since the ultimate effect of this research and any resulting policy action will be to reduce exposure to smoking and decrease smoking (albeit by a lower amount than 44%), it is ultimately not a problem?

I think it is a problem, however, for two reasons.

First, I think that despite all this scientific work being for a great cause, it ultimately hurts the science base for tobacco control in general to have specific claims being made from studies that do not support those claims. It is only an observation, but it certainly seems to me that the rigor required before we start making these kinds of precise quantitative claims has decreased over the years in which I have been doing research in this field. Ultimately, I guess that I am concerned somewhat about the credibility of tobacco control research findings among the public if they are continually exposed to these types of quantitative claims being made from research designs that are simply not "designed" to produce such claims.

Second, if, for the reasons I have outlined above, the claim is an overestimate, then we will fail to see the expected decline in youth smoking if we do address the problem definitively. So even if we were to ban all smoking in movies tomorrow, I very much doubt that we would subsequently see a 44% reduction in youth smoking initiation.

In fact, there is evidence to support this contention. After all, the Legacy press release claims that there was a doubling of youth exposure to smoking in youth-rated movies between 2010 and 2012. Further, there was a 169% increase in tobacco impressions in youth-rated movies between 2010 and 2013.

If it were true that smoking in movies is responsible for 44% of youth smoking initiation, then certainly we would have expected to see an increase in smoking initiation over the past three years, concurrent with this drastic increase in smoking in movies. However, the opposite is the case. Smoking among youth is now at an all-time low. It has declined significantly, rather than increased drastically, during the past three years.

These data hardly seem consistent with the claim that smoking in movies - alone - is responsible for 44% of youth smoking initiation.

An even more significant problem is that of confounding. Youths do not randomly choose to watch or not watch films that are likely to show lots of smoking. Some of the factors that predict what movies a youth is likely to view are also likely to predict their risk of smoking initiation. It is difficult to identify, much less quantify and measure these variables, and the existing studies have controlled for a few potential confounders, but not for many of them.

For these reasons, I think it is scientifically unsupportable for the American Legacy Foundation to claim that 44% of all smoking initiation is caused by exposure to smoking in movies.

Does smoking in movies contribute towards media exposure that influences youth smoking?

Absolutely.

Should we take efforts to reduce youth exposure to smoking in movies and other media?

Absolutely.

But I don't think we do ourselves any favors when we go beyond the science and make sweeping, yet quantitatively precise claims like this one from Legacy. Ultimately, it hurts our scientific credibility and undermines the integrity of our work.

1 comment:

Anonymous said...

Should we take efforts to reduce youth exposure to smoking in movies and other media?

Absolutely.

Ah, back in form I see, and so soon after your recent disillusionment.. So you favor censorship and only quibble over what imaginary percentage of Children you will save by further eroding everyone's freedoms of speech and choice

I don't know why I'm given this blank form and asked to prove I'm not a robot but this is from

Walt.