Is the US Rate of Veganism and Vegetarianism Increasing? A Meta-Analysis

Creating more vegans and vegetarians has been one of the major goals of the animal advocacy movement at large for decades. To evaluate the success of those efforts, one crucial step is to assess the current rates of veganism and vegetarianism in the United States as well as changes in those rates over time. While many surveys and opinion polls by different organizations have estimated the rates of veganism and vegetarianism over the years, their results have varied widely, potentially due to small sample sizes and variations in survey methods. In this project, we will use meta-analytic methods to derive more precise estimates and confidence bounds for the current rates of US veganism and vegetarianism and detect potential changes in these rates over time. As a first step, we will collect the results of all known surveys and polls asking participants whether they identify as vegan or vegetarian. We will then conduct three separate Bayesian meta-analyses estimating the rates of vegans, vegetarians, and all people identifying as either vegan or vegetarian. Lastly, we will evaluate linear and non-linear temporal trends in the rate of veganism and vegetarianism in the US by adding the date each survey was conducted as a predictor in the meta-analytic model.