Linear regressions with period and group fixed effects are widely used to estimate treatment effects. We show that they identify weighted sums of the average treatment effects (ATE) in each group and period, with weights that may be negative. Due to the negative weights, the linear regression...

To estimate causal effects from observational data, an applied researcher must impose beliefs. The instrumental variables exclusion restriction, for example, represents the belief that the instrument has no direct effect on the outcome of interest. Yet beliefs about instrument validity do not...

This paper describes how three money's worth measures the benefit-to-tax ratio, the internal rate of return, and the net present value are calculated and used in analyses of social security reforms, including systems with privately managed individual accounts invested in equities. Declining...

Many advocates of social security privatization argue that rates of return under a defined contribution individual account system would be much higher for all than they are under the current social security system. This claim is false. The mistake comes from ignoring accrued benefits already...

This paper presents a new, dynamic economic model of criminal activity. Individuals are endowed with legal and criminal human capital. Potential incomes in legal and criminal sectors depend on the level of the relevant human capital, the rate of return, and random shocks. Both types of human...

In this paper we study the transition from a pay-as-you-go system of Social Security pensions to an investment-based system in an economy in which portfolio returns and capital profitability are both uncertain. The paper extends earlier studies by Feldstein and Samwick that modeled the...

We propose an approach to measuring the state of the economy via textual analysis of business news. From the full text of 800,000 Wall Street Journal articles for 1984-2017, we estimate a topic model that summarizes business news into interpretable topical themes and quantifies the proportion of...

Measured as yield spreads against AAA corporate bonds, the convenience premium of agency MBS averages 47 basis points over 1995 - 2021, about half of the long-term-Treasury convenience premium. Both MBS convenience premium and issuance amount depend on mortgage rate negatively, consistent with a...