We develop a leverage theory of tying in markets with network effects. When a monopolist in one market cannot perfectly extract surplus from consumers, tying can be a mechanism through which unexploited consumer surplus is used as a demand-side leverage to create a “quasi-installed base” advantage in another market characterized by network effects. Our mechanism does not require any precommitment to tying; rather, tying emerges as a best response that lowers the quality of tied-market rivals. While tying can lead to exclusion of tied-market rivals, it can also expand use of the tying product, leading to ambiguous welfare effects.

Item-level transactions data yield cost-of-living indices that can account for quality change and consumer substitution. Transactions data require confronting the rapid turnover of items because prices of new and existing products are interrelated in equilibrium. This paper evaluates multiple approaches to measuring quality change at scale. It shows that a hedonic superlative approach—using econometrics or machine learning for hedonic estimation combined with index formulas that require simultaneous observation of item-level price and expenditure—yields improved measures of the cost of living. Accounting for ubiquitous quality change and for consumer substitution yields lower measures of inflation than traditional, official methods.

We study the welfare impacts of 96 climate-related tax and spending policies. We extend and apply the marginal value of public funds (MVPF) framework, most notably providing a new method for incorporating learning-by-doing spillovers. We find subsidies for the production of clean energy (such as wind production tax credits) have higher MVPFs than all other subsidies in our sample, including EV subsidies. Conservation nudges have large MVPFs when targeting regions with dirty grids. Fuel taxes and cap-and-trade policies are highly efficient means of raising revenue. We also construct traditional cost-per-ton estimates and compare and contrast the lessons they provide.

This paper examines the effects of privatizing social health insurance in the United States. We study this question in the context of the Medicaid program, the largest health insurer in the US and the largest means-tested program in the nation -serving over 90 million low-income families and individuals with disabilities. Exploiting a natural experiment wherein nearly 100,000 Medicaid enrollees were randomly assigned between a state-administered fee-for-service system and private managed care, we find that spending was nearly 10% lower for enrollees assigned to managed care plans. These savings were concentrated in prescription drugs, where we show that prior authorization was the key mechanism plans used to reduce overuse and encourage substitution to lower-cost alternatives without reducing quality. This was distinct from the effects of privatization on medical benefits, where private plans lowered quality and abraded consumers without achieving savings. In contrast to what our findings imply for an efficient public-private division of services, Medicaid has historically favored the public provision of prescription drugs and private outsourcing of medical care.