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The number who use calorie information, though still small compared to those who do not, is still much higher in the CDC study—nearly four times as high—than the number who use calorie information in the NYU study.
Why the discrepancy? I can’t say for sure. However, I suspect the difference arises largely from the CDC researchers’ total reliance on self-reporting of data by teens and adolescents.
In the NYU study, researchers collected purchase receipts from 349 teens, adolescents, and their families who visited fast food/chain restaurants both before and after the implementation of New York City’s menu-labeling law.
That’s hard data.
The CDC study, on the other hand, collected data from the self-reported YouthStyles survey given to teens and adolescents nationwide. They analyzed data from respondents who said they “ate at fast food restaurants and noticed the [calorie] information while ordering.”
Furthermore, while the CDC authors report that “some fast food/chain restaurants have begun to post [calorie] information voluntarily,” the data Wethington and her colleagues analyzed comes exclusively from 2010.
That date largely precedes both voluntary and mandatory menu labeling (in which calorie information is posted alongside menu items). McDonald’s, the largest national fast food/chain restaurant to post calorie information, did not begin doing so nationwide until 2012. Other competitors may follow (before a mandatory national law takes effect sometime in the future), but few have done so to date.
Meanwhile, the largest jurisdictions to participate in the YouthStyles survey the CDC analyzed and which also had menu-labeling laws in 2010, according to this April 2011 map created by the Center for Science in the Public Interest (CSPI), were New York City and the state of California.
But data from those two key places is slim. The CDC study authors note that they did not collect sufficient data for New York City, stating respondents included “too few youth from NYC.” Meanwhile, it appears only a maximum of 13 percent of survey respondents hailed from California (which is presumably part of the study’s results for its “Pacific” region).
What about menu labeling outside New York City and California? An overwhelming majority, 39 out of 50 states, had no menu-labeling laws within their borders whatsoever in 2010, according to the CSPI map. Nine of the 11 states had only one or more municipal laws (e.g., Philadelphia had a law in place but Pennsylvania and every other city in the state did not) and only two states (Vermont being the second) had implemented menu-labeling laws.
How can so many young Americans have claimed to “notice[ calorie] information while ordering” in cities and states where restaurants most often don’t provide that information at the point of sale (though many do online, or elsewhere in stores)?
In short, I believe that many of the 9-18 year-old survey respondents were for whatever reason mistaken in their response to the question about whether they use calorie information provided in a fast food/chain restaurants to inform their decisions.
If I’m right, then that would make the validity of the CDC researchers’ study, based wholly on these responses, open to debate—something that holds true for an increasing number of studies in the area of food law and policy.