About

Sofia Berto Villas-Boas is the Class of 1934 Robert Gordon Sproul Distinguished Professor in Agricultural Economics and a Professor of Agricultural and Resource Economics at the University of California, Berkeley. She serves as the Department Chair of the Department of Agricultural and Resource Economics. Born in Portugal in 1971, she received her Ph.D. in Economics from UC Berkeley in May 2002. Her research interests include industrial organization, consumer behavior, food policy, and environmental regulation. Her recent empirical work estimates the effects of various policies on consumer behavior, including product labeling changes, a bottled water tax, a plastic bag ban, and a soda tax campaign as well as its implementation. Other published work has focused on the economics behind wholesale price discrimination banning legislation, contractual relationships along a vertical supply chain, and identifying the role of those contracts in explaining pass-through of cost shocks along the supply chain into retail prices that consumers face. She has published in top economics and field journals such as The Review of Economic Studies, RAND Journal of Economics, American Journal of Agricultural Economics, Journal of Environmental Economics and Management, Marketing Science, Management Science, and Review of Economics and Statistics. She teaches Quantitative Policy Analysis using Structural Modeling and Applied Econometrics in the Agricultural and Resource Policy field in the ARE Ph.D. program and Econometrics in the undergraduate Environmental Economics and Policy major at the Rausser College of Natural Resources.

Selected publications

• Do Patents Predict Innovation?

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Does automation reduce stigma? The effect of self-checkout register adoption on purchasing decisions

  Journal of Economic Behavior & Organization · 2025-07-20 · 2 citations

  articleOpen accessSenior author

  By removing human cashiers, self-checkout registers may alter feelings of embarrassment experienced by customers. Using high-frequency scanner data from supermarkets in the Washington, D.C. area with staggered adoption of self-checkout, we conduct event study analyses on consumer purchasing behavior. On the extensive margin, we find positive but noisy effects of self-checkout adoption on sales of some stigmatized items. On the intensive margin, we show that stigmatized items are much more likely to be purchased at self-checkout than at cashier registers, especially condoms and pregnancy tests. We estimate that customers are willing to pay 8.5 cents in additional time cost for the privacy of purchasing stigmatized items at self-checkout.

  PublisherDOI

• Evaluation of Changes in Prices and Purchases Following Implementation of Sugar-sweetened Beverage Taxes Across the United States

  SSRN Electronic Journal · 2024-01-01

  articleOpen access
  PublisherDOI

• De-normalizing sugar-sweetened beverage consumption: effects of tax measures on social norms and attitudes in the California Bay Area

  BMC Public Health · 2024-11-25 · 2 citations

  articleOpen access

  BACKGROUND: Social norms can influence individual health behaviors. Shifts in social norms for smoking were critical for the effectiveness of tobacco control efforts such as excise taxes. Sugar-sweetened beverage (SSB) excise taxes have been implemented in municipalities across the United States to reduce SSB intake and improve health. We sought to identify trends in social norms and attitudes about healthfulness of sugar-sweetened beverage (SSB) consumption in the California Bay Area and examine whether social norms and attitudes changed following SSB taxes. METHODS: Data came from annual (2016-2019, 2021) cross-sectional surveys (n = 9128) in lower-income neighborhoods in Oakland, San Francisco, Berkeley, and Richmond. We assessed overall trends and compared pre-post tax changes in Oakland and San Francisco with comparison cities. RESULTS: We observed a 28% reduction in social norms for SSB consumption (people's perceptions of peers' consumption) and variable reductions in attitudes about the healthfulness of SSBs. Relative to comparison cities, post-tax, perceptions of peers' consumption of sports drinks declined in Oakland; attitudes about the healthfulness of sugar-sweetened fruit drinks declined in San Francisco. CONCLUSIONS: Among lower-income populations, social norms and attitudes towards the healthfulness of SSBs meaningfully declined over time, with smaller tax-related effects. SSB taxes as well as the local media attention they generate appear to affect people's perceptions of SSBs. Pairing SSB taxes with messaging campaigns may be more effective in de-normalizing SSB consumption.

  PublisherOA PDFDOI

• Evaluation of Changes in Prices and Purchases Following Implementation of Sugar-Sweetened Beverage Taxes Across the US

  JAMA Health Forum · 2024-01-05 · 30 citations

  articleOpen access

  Importance: Sugar-sweetened beverage (SSB) taxes are promoted as key policies to reduce cardiometabolic diseases and other conditions, but comprehensive analyses of SSB taxes in the US have been difficult because of the absence of sufficiently large data samples and methods limitations. Objective: To estimate changes in SSB prices and purchases following SSB taxes in 5 large US cities. Design, Setting, and Participants: In this cross-sectional study with an augmented synthetic control analysis, changes in prices and purchases of SSBs were estimated following SSB tax implementation in Boulder, Colorado; Philadelphia, Pennsylvania; Oakland, California; Seattle, Washington; and San Francisco, California. Changes in SSB prices (in US dollars) and purchases (volume in ounces) in these cities in the 2 years following tax implementation were estimated and compared with control groups constructed from other cities. Changes in adjacent, untaxed areas were assessed to detect any increase in cross-border purchases. Data used for this analysis spanned from January 1, 2012, to February 29, 2020, and were analyzed between June 1, 2022, and September 29, 2023. Main Outcomes and Measures: The main outcomes were the changes in SSB prices and volume purchased. Results: Using nutritional information, 5500 unique universal product codes were classified as SSBs, according to tax designations. The sample included 26 338 stores-496 located in treated localities, 1340 in bordering localities, and 24 502 in the donor pool. Prices of SSBs increased by an average of 33.1% (95% CI, 14.0% to 52.2%; P < .001) during the 2 years following tax implementation, corresponding to an average price increase of 1.3¢ per oz and a 92% tax pass-through rate from distributors to consumers. SSB purchases declined in total volume by an average of 33.0% (95% CI, -2.2% to -63.8%; P = .04) following tax implementation, corresponding to a -1.00 price elasticity of demand. The observed price increase and corresponding volume decrease immediately followed tax implementation, and both outcomes were sustained in the months thereafter. No evidence of increased cross-border purchases following tax implementation was found. Conclusions and Relevance: In this cross-sectional study, SSB taxes led to substantial, consistent declines in SSB purchases across 5 taxed cities following price increases associated with those taxes. Scaling SSB taxes nationally could yield substantial public health benefits.

  PublisherOA PDFDOI

• Influence of Telecommuting on Out-of-Home Time Use and Diversity of Locations Visited: Evidence from the Covid-19 Pandemic

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access
  PublisherDOI

• Influence of telecommuting on out-of-home time use and diversity of locations visited: Evidence from the COVID-19 pandemic

  Transportation Research Part A Policy and Practice · 2024-10-02 · 3 citations

  article
  PublisherDOI

• Does Automation Reduce Stigma? The Effect of Self-Checkout Register Adoption on Purchasing Decisions

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Patterns of US Mental Health–Related Emergency Department Visits During the COVID-19 Pandemic

  JAMA Network Open · 2023-07-11 · 18 citations

  articleOpen access1st author

  Importance: Numerous studies have shown that the prevalence of mental health (MH) conditions worsened during the COVID-19 pandemic. Further research is needed on this phenomenon over a longer time horizon that considers the increasing trend in MH conditions before the pandemic, after the pandemic onset, and after vaccine availability in 2021. Objective: To track how patients sought help in emergency departments (EDs) for non-MH and MH conditions during the pandemic. Design, Setting, and Participants: This cross-sectional study used administrative data on weekly ED visits and a subset of visits for MH from the National Syndromic Surveillance Program from January 1, 2019, to December 31, 2021. Data were reported from the 10 US Department of Health and Human Services (HHS) regions (Boston, New York, Philadelphia, Atlanta, Chicago, Dallas, Kansas City, Denver, San Francisco, and Seattle) for five 11-week periods. Data analysis was performed in April 2023. Main Outcomes and Measures: Weekly trends in total ED visits, mean MH-related ED visits, and proportion of ED visits for MH conditions were investigated to determine changes in each measure after the pandemic onset. Prepandemic baseline levels were established from 2019 data, and time trends of these patterns were examined in the corresponding weeks of 2020 and 2021. A fixed-effects estimation approach with weekly ED region data by year was used. Results: There were 1570 total observations in this study (52 weeks in 2019, 53 weeks in 2020, and 52 weeks in 2021). Statistically significant changes in non-MH and MH-related ED visits were observed across the 10 HHS regions. The mean total number of ED visits decreased by 45 117 (95% CI, -67 499 to -22 735) visits per region per week (39% decrease; P = .003) in the weeks after the pandemic onset compared with corresponding weeks in 2019. The mean number of ED visits for MH conditions (-1938 [95% CI, -2889 to -987]; P = .003) decreased significantly less (23% decrease) than the mean number of total visits after the onset of the pandemic, increasing the mean (SD) proportion of MH-related ED visits from 8% (1%) in 2019 to 9% (2%) in 2020. In 2021, the mean (SD) proportion decreased to 7% (2%), and the mean number of total ED visits rebounded more than that of mean MH-related ED visits. Conclusions and Relevance: In this study, MH-related ED visits demonstrated less elasticity than non-MH visits during the pandemic. These findings highlight the importance of addressing the provision of adequate MH services, both in acute and outpatient settings.

  PublisherOA PDFDOI

• Evaluation of the sugar-sweetened beverage tax in Oakland, United States, 2015–2019: A quasi-experimental and cost-effectiveness study

  PLoS Medicine · 2023-04-18 · 17 citations

  articleOpen accessCorresponding

  BACKGROUND: While a 2021 federal commission recommended that the United States government levy a sugar-sweetened beverage (SSB) tax to improve diabetes prevention and control efforts, evidence is limited regarding the longer-term impacts of SSB taxes on SSB purchases, health outcomes, costs, and cost-effectiveness. This study estimates the impact and cost-effectiveness of an SSB tax levied in Oakland, California. METHODS AND FINDINGS: An SSB tax ($0.01/oz) was implemented on July 1, 2017, in Oakland. The main sample of sales data included 11,627 beverage products, 316 stores, and 172,985,767 product-store-month observations. The main analysis, a longitudinal quasi-experimental difference-in-differences approach, compared changes in beverage purchases at stores in Oakland versus Richmond, California (a nontaxed comparator in the same market area) before and 30 months after tax implementation (through December 31, 2019). Additional estimates used synthetic control methods with comparator stores in Los Angeles, California. Estimates were inputted into a closed-cohort microsimulation model to estimate quality-adjusted life years (QALYs) and societal costs (in Oakland) from 6 SSB-associated disease outcomes. In the main analysis, SSB purchases declined by 26.8% (95% CI -39.0 to -14.7, p < 0.001) in Oakland after tax implementation, compared with Richmond. There were no detectable changes in purchases of untaxed beverages or sweet snacks or purchases in border areas surrounding cities. In the synthetic control analysis, declines in SSB purchases were similar to the main analysis (-22.4%, 95% CI -41.7% to -3.0%, p = 0.04). The estimated changes in SSB purchases, when translated into declines in consumption, would be expected to accrue QALYs (94 per 10,000 residents) and significant societal cost savings (>$100,000 per 10,000 residents) over 10 years, with greater gains over a lifetime horizon. Study limitations include a lack of SSB consumption data and use of sales data primarily from chain stores. CONCLUSIONS: An SSB tax levied in Oakland was associated with a substantial decline in volume of SSBs purchased, an association that was sustained more than 2 years after tax implementation. Our study suggests that SSB taxes are effective policy instruments for improving health and generating significant cost savings for society.

  PublisherOA PDFDOI

Awards & honors

• Class of 1934 Robert Gordon Sproul Distinguished Professor i…