Learning from Seller Experiements in Online Markets

The internet has dramatically reduced the cost of varying prices, dis- plays and information provided to consumers, facilitating both active and passive experimentation. We document the prevalence of targeted pricing and auction design variation on eBay, and identify hundreds of thousands of experiments con- ducted by sellers across a wide array of retail products. We show how this type of data can be used to address questions about consumer behavior and market outcomes, and provide illustrative results on price dispersion, the frequency of over-bidding, the choice of reserve prices, ?buy now?options and other auction design parameters, and on consumer sensitivity to shipping fees. We argue that leveraging the experiments of market participants takes advantage of the scale and heterogeneity of online markets and can be a powerful approach for testing and measurement.

Social Capital and Economic Mobility

In recent years, social scientists have identified many factors that facilitateupward income mobility, from early childhood health interventions toelementary school improvements to sectoral job training programs. Inaddition to these approaches, many have argued that social capital – thestrength of an individual's social network and community – may be animportant factor in upward mobility. But social capital has proven to bechallenging to measure, making it difficult to study whether it matters,and, if it does, how it can be increased.To address this challenge, we use privacy-protected data on 21 billionfriendships from Facebook to measure three types of social capital incommunities across America

Learning from Seller Experiments in Online Markets

The internet has dramatically reduced the cost of varying prices, displays and information provided to consumers, facilitating both active and passive experimentation. We document the prevalence of targeted pricing and auction design variation on eBay, and identify hundreds of thousands of experiments conducted by sellers across a wide array of retail products. We show how this type of data can be used to address questions about consumer behavior and market outcomes, and provide illustrative results on price dispersion, the frequency of over-bidding, the choice of reserve prices, "buy now" options and other auction design parameters, and on consumer sensitivity to shipping fees. We argue that leveraging the experiments of market participants takes advantage of the scale and heterogeneity of online markets and can be a powerful approach for testing and measurement.

The Effect of the COVID-19 Pandemic on Patient Selection, Surgical Procedures, and Postoperative Complications in a Specialized Dental Implant Clinic.

During the coronavirus disease 2019 (COVID-19) pandemic, aerosol-generating procedures, including dental implant treatments, are considered high-risk. With dental implant treatment mostly an elective procedure, we aimed to assess whether the pandemic influenced patient selection, surgical procedures, and postoperative complications. We compared dental implant treatments during (March to December 2020) and before (December 2018 to February 2020) the COVID-19 pandemic based on patient and implant parameters, as well as postoperative complications. For analysis, we used the Chi-squared test with the Holm-Sidak correction for multiple comparisons. The number of implants placed during the COVID-19 pandemic (696 implants in 406 patients, 70 implants per month) was comparable to pre-pandemic levels (1204 implants in 616 patients, 80 implants per month). Regarding patient parameters, there were no significant differences in respiratory (p = 0.69) and cardiovascular conditions (p = 0.06), diabetes (p = 0.69), and smoking (p = 0.68). Regarding implant parameters, there was a significant difference in the distribution of augmentative procedures (no augmentation, guided bone regeneration, and sinus floor elevation, p = 0.01), but no significant differences in the types of edentulous spaces (p = 0.19) and the timing of implant placement (p = 0.52). Regarding complications, there were significantly fewer minor complications (p < 0.001) and early (i.e., before loading) implant failures (p = 0.02) compared with pre-pandemic levels. Our results suggest that the COVID-19 pandemic had no effect on patient selection and only a slight effect on the surgical procedures. However, postoperative complications, including early failures, were significantly less prevalent during the pandemic