Alexia Olaizola

This paper studies variance estimators in panel data settings. There has been a recent surge in research on panel data models with a number of new estimators proposed. However, there has been less attention paid to the quantification of the precision of these estimators. Of the variance estimators that have been proposed, their relative merits are not well understood. In this paper we develop a common framework for comparing some of the proposed variance estimators for generic point estimators. We reinterpret three commonly used approaches as targeting different conditional variances under an exchangeability assumption. We find that the estimators we consider are all valid on average, but that their performance in terms of power differs substantially depending on the heteroskedasticity structure of the data. Building on these insights, we propose a new variance estimator that flexibly accounts for heteroskedasticity in both the unit and time dimensions, and delivers superior statistical power in realistic panel data settings.

Federal court decisions can reshape local governments’ enforcement authority, but their impact depends on how cities adapt. Between 2018 and 2024, federal rulings restricted Western U.S. cities’ ability to cite individuals for sleeping or camping in public unless adequate shelter was available. This limitation was widely blamed for rising visible homelessness. Using novel data on enforcement and homelessness from over 50 cities along with a synthetic difference-in-differences design, we find no evidence that the rulings substantially reduced enforcement or increased visible homelessness. Cities responded heterogeneously: some curtailed citations, while others maintained enforcement through alternative mechanisms such as encampment clearings. When the Supreme Court reversed the restrictions in 2024, citations rose but homelessness did not decline. These results suggest that federal constraints on local enforcement have limited effects when cities can adapt along unregulated margins, and that structural conditions such as housing costs and service capacity likely play a larger role in shaping unsheltered homelessness.

Supported by $75,000 grant from Arnold Ventures 

Encampment “sweeps” have become a central but controversial component of urban homelessness policy. We study their neighborhood impacts in Los Angeles, where over 75,000 people experience homelessness and sweep activity expanded sharply after a funding increase in 2019. Combining novel administrative data on encampment clearings with 311 service requests and LAPD incident reports from 2016–2023, we exploit the quasi-random timing of sweeps to estimate event studies. Sweeps lead to large and persistent declines in local 311 encampment complaints, but have no detectable effects on crime or foot traffic. These results suggest that sweeps reduce the visibility of homelessness without improving neighborhood safety. Ongoing work applies a staggered difference-in-differences design to assess causal impacts, and explores dynamic spatial spillovers and policy equilibrium effects through a model of homeless location choice. 

This paper examines the causal effects of foster care placement on children and their families using rich linked administrative data from the Government of British Columbia, Canada. We estimate the impact of placement on children’s outcomes, including physical and mental health, educational attainment, employment, and criminal justice involvement. For parents, we assess effects on mental health, housing stability, and social service utilization. For both children and parents, we further explore impacts on Indigenous identity and cultural continuity, measured through location of residence and self-identification as Indigenous. Our findings provide new evidence on the broader consequences of child welfare interventions for both generations.

This paper studies a series of public-school funding reforms in British Columbia, Canada from 1982-1991.  These reforms decreased expected funding in some school districts while raising it in others, leading to funding equalization across districts. Using these reforms as a source of exogenous variation in a simulated instrumental variables design, I evaluate the effects of changes in funding on student test scores, graduation rates, adult income and private school attendance. I examine potential mechanisms, and compare results across urban and rural school districts. 

There is a gap in the literature pertaining to the effects of drug insurance and cost-sharing in a Canadian context. We conducted a systematic review of Canadian studies and found that there was consistent evidence that the expansion of drug insurance was associated with meaningful increases in drug use, that individuals who reported drug insurance coverage generally reported higher drug use relative to those who reported no coverage, and that increases in and higher levels of drug cost-sharing were associated with lower use. Universal pharmacare without cost-sharing may reduce inequities in access to essential drugs.

In 2014, Ontario increased its “minimum wage“ for personal support workers (PSWs) in publicly funded home care. The objective of this article is to determine the short-term results of this policy for home care PSWs' wages, hours and job stability. This study uses descriptive graphs, ordinary least squares and unconditional quantile regressions, using PSWs across Canada as comparison groups. The policy increased home care PSWs' wages without noticeably affecting hours or job stability. However, wages were already increasing for low-wage home care workers in the rest of Canada. Ontario exercises monopsony power in the home care market and, before the wage increase, kept nominal wages stable compared to rising real and nominal wages in the rest of Canada. This PSW-specific wage increase did not represent a drastic change relative to market conditions.

This chapter documents changes from 2006 to 2016 in the number of physicians, registered nurses (RNs) and practical nurses (PNs) in Canada. It identifies those working in each occupation as well as those reporting relevant educational credentials but not working in the occupation. The number of practicing physicians and PNs grew at double the rate of the total workforce, whereas practicing RNs only grew at one-third that rate. The high physician growth rate was a result of education and immigration policies intended to address perceptions of increasing physician shortages. In contrast, the low RN and high PN growth rates likely reflect a shift to lower cost PNs with no growth in total nursing relative to the workforce. The growth rate of foreign-born, foreign-trained professionals working in all three professions was larger than the relevant occupation’s average growth rate. Despite this, the percentage of foreign-born, foreign-trained individuals not working in their trained profession also increased for physicians and RNs. The net effect is that the percentage of foreign-born, foreign-trained potential physicians and RNs working in their profession declined. This “brain waste” reflects mismatches between health and immigration policies.