My broad research interests are in applied macroeconomics, monetary and fiscal policy, public finance, housing and mortgage markets, and innovation and growth. My current research is focused on the returns to public R&D spending, U.S. business cycles and growth, and U.S. housing credit policy and secondary mortgage markets.


The Macroeconomic Effects of Government Asset Purchases: Evidence from Postwar U.S. Housing Credit Policy, joint with Karel Mertens and Morten O. RavnQuarterly Journal of Economics, 133 (3): 1503-1560. Online appendices.

Previously available as NBER Working Paper No. 23154. ASSA 2018 slidesVoxEU column.

We document the portfolio activity of federal housing agencies and provide evidence on its impact on mortgage markets and the economy. Through a narrative analysis, we identify historical policy changes leading to expansions or contractions in agency mortgage holdings. Based on those regulatory events that we classify as unrelated to short-run cyclical or credit market shocks, we find that an increase in mortgage purchases by the agencies boosts mortgage lending, in particular refinancing, and lowers mortgage rates. Agency purchases also influence prices in other asset markets, stimulate residential investment, and expand homeownership. We compare these effects to those of conventional monetary policy shocks, and we provide evidence on the interactions between housing credit and monetary policies.

Working Papers

The Returns to Government R&D: Evidence from U.S. Appropriations Shocks, joint with Karel Mertens. Online appendices.

We estimate the causal impact of government-funded R&D on business-sector productivity growth. Identification is based on a novel narrative classification of all significant postwar changes in appropriations for  R&D   funded by five major federal agencies. Using long-horizon local projections and the narrative measures, we find that an increase in appropriations for nondefense  R&D   leads to increases in various measures of innovative activity, and higher productivity in the long run. We structurally estimate the production function elasticity of nondefense government  R&D  capital using the SP-IV methodology of Lewis and Mertens (2023), and obtain implied returns of 150 to 300 percent over the postwar period. The estimates indicate that government-funded R&D  accounts for about one quarter of business-sector TFP growth since WWII, and generally point to substantial underfunding of nondefense R&D.

A New Claims-Based Unemployment Dataset: Application to Postwar Business Cycles for U.S. States, joint with Sean Howard, Christoffer Koch, and David Munro.

Revision requested, Brookings Papers on Economic Activity.

Previously available circulated as “A New Claims-Based Unemployment Dataset: Application to Postwar Recoveries Across U.S. States,” IMF Working Paper No. 2022/117. Latest slides.

Using newly digitized unemployment insurance claims data we construct a historical monthly unemployment series for U.S. states going back to January 1947. The constructed series are highly correlated with the Bureau of Labor Statics’ state-level unemployment data, which are only available from January 1976 onwards, and capture consistent patterns in the business cycle. We use our claims-based unemployment series to examine the evolving dynamics of post-war unemployment fluctuations at the state level. We find that faster national recoveries in unemployment are associated with greater heterogeneity in recovery rates across states and slower recoveries tend to be experienced more uniformly. In addition, we find that the pace of unemployment recoveries is positively correlated with states’ manufacturing share of output.

Crowd-out Effects of U.S. Housing Credit Policy. Latest slides.

Credit policies can expand targeted lending volumes by subsidizing private credit risks, and an expansion in targeted lending may crowd out other loans. I document that U.S. housing credit policies subsidizing an expansion in residential mortgage lending unintentionally crowd out commercial lending and related real activity. I use a long history of regulatory changes for exogenous variation in the mortgage purchases of Fannie Mae and Freddie Mac, government-sponsored enterprises that subsidize mortgage borrowing. Regulatory shocks to subsidized mortgage purchases crowd in private home mortgage lending while unintentionally crowding out commercial mortgages and loans. U.S. housing credit policies similarly reallocate construction activity toward housing and away from commercial real estate, negating any intended stimulus to aggregate construction or employment. I contribute evidence that the transmission of such mortgage purchases operates through a mortgage origination channel and a safe asset supply channel, which induce significant reallocations in bank lending. I explore implications for unwinding the Federal Reserve’s mortgage holdings and eventual reforms to Fannie and Freddie.

A Narrative Analysis of Mortgage Asset Purchases by Federal Agencies, joint with Karel Mertens, NBER Working Paper No. 23165 (updated July 2017). Online appendix.

This paper provides a narrative analysis of regulatory policy changes affecting the purchases and holdings of mortgages and related securities of five US government entities over the 1968–2014 period. We focus on federal government policies that aim to influence the allocation and/or volume of the supply of residential mortgage credit. We use contemporary primary sources and various institutional histories to identify significant policy interventions, to document their economic and regulatory context, surrounding motives, and pertinent timing, as well as to quantify projected impacts on agencies’ mortgage holdings. Finally, we classify each significant policy change as either “cyclically motivated” or “unrelated to the business and/or financial cycle.”

Work in Progress

A Narrative Analysis of Federal Appropriations for Research and Development, joint with Karel Mertens

This paper provides a narrative analysis of postwar federal appropriations for the research and development (R&D) activities of the Department of Defense, Department of Energy, National Aeronautics and Space Administration, National Institutes of Health, and National Science Foundation–five agencies that consistently account for the vast majority of federal outlays for all types of R&D. We build a novel data set quantifying the enacted full-year appropriations for all budgetary accounts funding R&D activities for each of these five agencies over FY1947-2019, which we use to identify a subset of “significant” changes in real appropriations for each agency. We then analyze numerous primary and secondary sources to understand the context and motivation for each significant policy change. Finally, we classify each significant change in federal R&D appropriations as either “endogenously motivated” or “exogenous.” The exogenous R&D appropriations shocks are intended as an instrumental variable for studying the causal effects of government R&D and have significant predictive power for changes in the government R&D capital stock.

Government-sponsored Secondary Mortgage Markets: Automatic Stabilizer for Housing?

Government-sponsored enterprises play a countercyclical role in U.S. mortgage markets, increasing mortgage purchases, expanding securitization volumes, and gaining market share during credit crunches. I estimate dynamic responses of the secondary market activity of Fannie Mae and Freddie Mac, mortgage and commercial lending, and housing market activity to monetary and financial shocks. Structural vector autoregressions (SVARs) are identified from the Gilchrist and Zakrajšek (2012) excess bond premium, the Gertler and Karadi (2015) measure of monetary shocks, and the Bloom (2009) measure of uncertainty shocks. Contractionary financial shocks induce an endogenous expansion of the mortgage purchases of Fannie and Freddie and the volume of agency-guaranteed mortgage securities. All three shocks are contractionary with respect to industrial production, consumption, and unemployment, but mortgage originations and home mortgage lending are insulated from financial shocks. I explore the historical contribution of secondary market activity in stabilizing mortgage lending across the credit cycle, as well as policy implications for reforms to Fannie and Freddie.

Complementarities Between Publicly Funded and Privately Funded R&D, joint with Adam Kolasinksi

Research Grants and Awards

Graduate School Conference Travel Grant, Cornell University, Fall 2018.

Dissertation Fellowship, Federal Reserve Board of Governors, Summer 2018.

Graduate School Conference Travel Grant, Cornell University, Spring 2018.

Graduate School Research Travel Grant, Cornell University, Fall 2017.

L.R. “Red” Wilson MA ‘67 Excellence in Economics Medal and Research Prize, Fall 2015.

External Research Profiles and Repositories