Slimmed Down Sourcing: Media Coverage of Soda Taxes

By S. Robert Lichter
March 21, 2011

The growing problem of obesity has created a wide-ranging debate over the ways public policy might be used to put America on a diet. One frequently debated solution is to make foods that contribute to obesity less desirable by making them more expensive. Ideally such measures, patterned after the “sin taxes” levied on tobacco and alcohol products, would slim down Americans while beefing up the depleted budgets of state and local governments.

This case also illustrates the growing role that academic experts play in health policy debates, by providing scientific analyses that range from the dietary effects of such substances to the role positive or negative incentives play in changing consumer behavior. An example is the ongoing battle over soda or soft drink taxes, which have recently been debated or enacted in localities across the country, from New York to Washington State. By studying the role experts play in setting the agenda on this relatively narrow issue, we hope to shed some light on the broader question of how academic or scientific experts influence the way health policy issues are framed more generally.

Some public health experts have called for taxing sugar-sweetened beverages and other drinks as a means of obesity reduction and dietary improvement. Others have questioned whether such measures would produce the desired behavioral changes. In the analysis that follows, we examine how the media have framed the role of experts in this debate. In addition to determining which experts attract the most attention, we investigate the ways the media evaluate competing expert perspectives.

Through a Factiva and Nexis Lexis search of print and electronic outlets between January 1, 2008 and December 31, 2010, we identified 340 news items referencing soda taxes. Print sources included wire service articles (such as AP and Reuters), daily newspapers, and general interest magazines (such as Newsweek and Forbes).

Electronic outlets included broadcast network news shows (ABC, CBS, NBC, and PBS), cable news network programming (CNN, MSNBC, and Fox News Channel), and National Public Radio.

We then identified all citations of expert sources on this topic, defined as references to the following types of institutions or individuals affiliated with them:

  • Colleges and Universities, including research centers affiliated with them,
  • Government agencies such as the Centers for Disease Control,
  • Professional associations such as the American Cancer Society.
  • In addition, we included material that was attributed to unnamed experts, in formats such as “many experts say…”.

A single citation was counted for each story in which an expert was mentioned or quoted, regardless of whether the source was cited more than once in the same story. This procedure identified 122 news items in which a total of 200 expert sources were cited.

One of the most notable findings was the concentration of sourcing. Two individuals accounted for almost two-thirds (65%) of all citations of named experts. These individuals were Dr. Kelly Brownell, Director of the Rudd Center for Food Policy and Obesity at Yale University, who accounted for 40 percent of all named sources; and Dr.Thomas Frieden, Director of the U.S. Centers for Disease Control, who accounted for 25 percent. Finishing a distant third with six percent of citations was Dr. Barry Popkin, a professor of nutrition at the University of North Carolina.  No other individual was cited more than twice.

This source concentration reflects the widespread publicity given to two scientific papers published in 2009 in the New England Journal of Medicine, which developed a case for using soda taxes as a means of reducing obesity. Brownell was lead author of both; one was co-authored with Frieden, the other with Popkin and several others. Brownell’s Rudd Center was mentioned an additional three times; the only other institution to be mentioned more than twice was the American Heart Association, which was cited nine times.

Within the time frame of the media coverage, however, four different studies were released that tried to model the effects of soda taxes. While the Brownell study got such widespread attention, the others received little mention in the media, although all called into question the strength of these effects.

This also illustrates the degree to which the media debate over the likely effects of soda taxes was framed in terms of public health rather than economics, insofar as academic expertise was brought to bear on this issue. Brownell, Frieden, and Popkin are experts in public health nutrition. (Brownell is a professor of psychology, epidemiology and public health at Yale. Frieden is a medical doctor. At the time his NEJM paper with Brownell was published, he was the health commissioner of New York City.) Of course, the effect of soda taxes on obesity is a cross-disciplinary issue that draws on principles of economic analysis as well as public health, nutrition, consumer psychology, and other fields. However, economists accounted for only one out of eight named sources (12%) who were cited on this issue.

Soda taxes will only curb consumption if they model consumption, elasticity and substitution effects accurately. But the economic literature shows wide disagreement on how these factors should be modeled, with economists reaching different conclusions about the efficacy of soda taxes, depending on the elasticity they give to sugar sweetened beverages. The health literature examining the relationship between soda consumption and weight gain, particularly with respect to children, shows even wider disagreement.

However, these controversies were not evident from the media coverage. In every instance in which an opinion on soda taxes was attributed to an expert source, we noted the nature and direction of opinion (positive, negative, or mixed). This produced a total of 248 opinions.

Sample positive opinion on soda taxes: “Using a tax, much as has happened with tobacco, to try to change consumption patterns in a way that would benefit overall public health and provide a very much-needed revenue for programs seems like a home run.”  — Kelly Brownell, NPR “Morning Edition,” October 14, 2009

Sample negative opinion on soda taxes: “The research is conflicting, however, especially when it comes to the efficacy of soda taxes. A study last month from the Rand Corp. concluded that small sales taxes on soft drinks are insufficient to significantly reduce consumption of soda or curb obesity among children.” — Washington Post, May 2, 2010
When all such opinions were aggregated, ninety percent supported soda taxes, seven percent opposed them, and four percent were mixed, combining both positive and negative elements. (The categories add up to 101% due to rounding error.) As a subset of the overall structure of opinion, we examined expert opinions on three major areas of contention that emerged from the study:

  • Will a soda tax curb obesity? (54 pinions);
  • Will a tax curb the consumption of soda? (56 opinions); and,
  • Will the economic effects of a soda tax be positive or negative? (63 opinions)

Most of the remaining opinions expressed support or opposition to soda taxes without offering a specific rationale.

Opinion on these specific rationales for a soda tax echoed the overall portrait of expert opinion:

On the issue of whether taxes would reduce obesity: 91 percent of opinions agreed that taxes would have this effect, while nine percent disagreed…

  • On the issue of whether higher taxes would reduce consumption (the rationale that was frequently given as the mechanism by which behavior would be affected) 93 percent affirmed this position, four percent opposed it and four percent of opinions were mixed.
  • Finally, on the most frequently debated issue, that of economic effects being positive (e.g., that it would raise needed revenue), 92 percent agreed, five percent disagreed, and three percent of opinions were mixed.

However, missing from the media coverage are the voices of leading economists working on taxation, such as Harvard’s Mehir Desai and Michigan’s Joel Slemrod, who were never cited during the time frame we examined. Nor were the economists who actually published major research on soda taxation during this time period. And anyone who researches the topic would know that there has been a lively debate over the efficacy of soda taxes and other “sin taxes.”

For example, a recent article in the Journal of Public Economics concludes, “These tax proposals have been offered with little evidence to assess their potential effectiveness. In fact, most of the rigorous evidence that exists appears to suggest limited effectiveness.”

It is also noteworthy that the distribution of opinion was very similar for both news stories and opinion pieces such as editorials and op-ed columns (which is why we combined the results for greater statistical power). In fact, opinions cited in news stories were slightly more supportive of soda taxes. Ninety one percent of 191 opinions in news stories favored the tax, five percent opposed them, and four percent were mixed. Of the 57 experts cited in opinion pieces, 86 percent favored the taxes, twelve percent opposed them, and two percent were mixed.

Thus, neither news reporters and editors nor editorial staffs seem to have perceived this issue as one that produced a significant division of opinion among experts, or as a controversy that required significant input from economists, despite the obvious economic inferences that underlie the debate.

Setting aside which side is correct on the issue, the central flaw in the media coverage is that the public debate is impoverished when expert sourcing is so narrowly focused that an entire discipline virtually disappears from the view of the general news audience, particularly when that discipline’s subject matter is so central to the issue at hand.



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