You may remember the discussion surrounding a research paper released back in August that used interviews and survey data to suggest that the tax on sodas that went into place in Berkeley caused a significant reduction in soda consumption.
As several other locales are considering new soda taxes in the upcoming election season, this sort of research is valuable in trying to sort out the potential effects of the policies.
Now there is new research by Scott Kaplan, Rebecca Taylor, and Sofia Villas-Boas at UC Berkely. The authors utilize a dataset on retail sales of various drinks in dining locations at "a large university" - presumably Berkeley. Importantly, the authors do not actually look at the effect of the implementation of the tax, but rather they look at what happened to soda sales because of the publicity and information surrounding the vote. That is, they look at soda sales surrounding the time of the vote but before the tax actually went into place.
Here is a figure from the paper summarizing the main findings:
The authors write:
My take on the results is that these soda tax policies may well have sizable "signaling" or "information" effects aside from whatever pecuniary effects exist. I have found similar results related to animal welfare regulations: that the publicity surrounding a vote has a significant impact on what people buy aside from whatever impacts the policy actually has on the price or foods offered. In short: information dissemination campaigns may be as important or more important than taxes or bans on products. In my assessment, information policies are often far more justifiable than are more coercive policies that restrict choice.
It will be interesting to see as future research emerges whether and how the actual implementation of the tax changes soda consumption and how long lasting are these information effects.