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Soda taxes: a 1% higher tax on soda than on other food items

Public Health & Prevention: Population-level policies
  Literature review updated November 2015.

Our review included two rigorous studies that investigated the relationship between a) taxes on soda that are greater than taxes on other food items, and b) obesity. One study examined the impact of soda taxes on children ages 3-18 and the other study examined the impact of soda taxes on adults at least 18 years of age. The effects presented here reflect a 1% increase in soda taxes beyond typical food tax rates.
 
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META-ANALYSIS
CITATIONS

Meta-analysis is a statistical method to combine the results from separate studies on a program, policy, or topic to estimate its effect on an outcome. WSIPP systematically evaluates all credible evaluations we can locate on each topic. The outcomes measured are the program impacts measured in the research literature (for example, impacts on crime or educational attainment). Treatment N represents the total number of individuals or units in the treatment group across the included studies.

An effect size (ES) is a standard metric that summarizes the degree to which a program or policy affects a measured outcome. If the effect size is positive, the outcome increases. If the effect size is negative, the outcome decreases. See Estimating Program Effects Using Effect Sizes for additional information on how we estimate effect sizes.

The effect size may be adjusted from the unadjusted effect size estimated in the meta-analysis. Historically, WSIPP adjusted effect sizes to some programs based on the methodological characteristics of the study. For programs reviewed in 2024 or later, we do not make additional adjustments, and we use the unadjusted effect size whenever we run a benefit-cost analysis.

Research shows the magnitude of effects may change over time. For those effect sizes, we estimate outcome-based adjustments, which we apply between the first time ES is estimated and the second time ES is estimated. More details about these adjustments can be found in our Technical Documentation.

Meta-Analysis of Program Effects
Outcomes measured No. of effect sizes Treatment N Effect sizes (ES) and standard errors (SE) Unadjusted effect size (random effects model)
ES SE Age ES p-value
Obesity
Obese based on clinical guidelines for adults (body mass index of 30 or higher) or children (body mass index at or above the 95th percentile for children of the same age and sex), as appropriate.
45 2 1365734 0.000 0.001 45 0.000 0.857

Citations Used in the Meta-Analysis

Fletcher, J., Frisvold, D., & Tefft, N. (2009). The Effects of Soft Drink Taxes on Child and Adolescent Consumption and Weight Outcomes, working paper.

Fletcher, J.M., Frisvold, D., & Tefft, N. (2010). Can soft drink taxes reduce population weight? Contemporary Economic Policy, 28(1), 23-35.