Resolving the Identification Problem in Linear Social Interactions Models: Modeling with Between-Group Spillovers

The linear-in-means model has been a theoretical and empirical workhorse of the social interactions field. As was noted by Manski (1993), the collinearity between group-level 'contextual' and 'endogenous' effects leads to an inability to identify the structural parameters of this model. Manski called this the 'reflection' problem. This paper suggests that Manksi’s reflection problem is unique to a special case of a more general context in which agents care about multiple reference groups. Specifically, the identification problem is resolved through a model generalization to include between-group and within-group effects.Social Interactions, Identification, Linear-in- Means Model

Monetary policy and capital regulation in the US and Europe

From the onset of the 2007-2009 crisis, the Federal Reserve and the European Central Bank have aggressively lowered interest rates. Both sets of changes are at odds with an anti-inflationary stance of monetary policy; indeed, as the crisis began in August 2007 inflation expectations were high and rising, particularly in the United States. We have two additions to the literature. One, we present a model economy with a leveraged and regulated financial sector. Two, we find optimal Taylor rules for our economy that are consistent with a strong pro-inflationary reaction during financial crisis while maintaining a standard output-inflation mandate. We have three interpretations of our results. One, because the Federal Reserve has partial control over bank regulation it can exercise regulatory lenience. Two, the Fed’s stronger output orientation means that it will potentially respond more quickly when faced with constrained banks. Three, our results support procyclical capital regulation. JEL Classification: E52, E58, G18, G28capital regulation, crisis, monetary policy

Welfare Stigma or Information Sharing? Decomposing Social Interactions Effects in Social Benefit Use

Empirical research has shown that social interactions affect the use of public benefits, thus providing evidence in favor of the idea of “welfare cultures.” In this paper we take the next crucial step by separately identifying the role of social stigma and information sharing in welfare participation, using Census data. We argue that the stigma vs. information distinction has possibly important consequences. Separate identification exploits the asymmetry between association and mere spatial proximity: we asume that while information is transmitted within groups, stigma works across groups as well. We also allow for heterogeneity of social effects across different race-ethnic groups and find non-trivial differences. We find that while the information channel is more important than stigma, White Americans appear to perceive stigma more from otherWhite Americans than by other races, and Black and Hispanic Americans appear to respond principally to stigma from external groupssocial interactions, neighborhood effects, welfare stigma

The Balance Sheet Channel

In this paper, we study the role of the credit channel of monetary policy in the context of a DSGE model. Through the use of a regulated banking sector subject to a regulatory capital constraint on lending, we provide alternative interpretations that can potentially explain differences in the implementation of monetary policy without appealing to ad-hoc central bank preferences. This is accomplished through the characterization of the external finance premium as a function of bank leverage and systemic aggregate risk.

Systemic Risk and Network Formation in the Interbank Market

We propose a novel mechanism to facilitate understanding of systemic risk in financial markets. The literature on systemic risk has focused on two mechanisms, common shocks and domino-like sequential default. Our approach is a formal model that provides an intellectual combination of the two by looking at how shocks propagate through a network of interconnected banks. Transmission in our model is not based on default. Instead, we provide a simple microfoundation of banks’ profitability based on classic competition incentives. As competitors lending quantities change, both for closely connected ones and the whole market, banks adjust their own lending decisions as a result, generating a ‘transmission’ of shocks through the system. We provide a unique equilibrium characterization of a static model, and embed this model into a full dynamic model of network formation with n agents. Because we have an explicit characterization of equilibrium behavior, we have a tractable way to bring the model to the data. Indeed, our measures of systemic risk capture the propagation of shocks in a wide variety of contexts; that is, it can explain the pattern of behavior both in good times as well as in crisis.Financial networks; interbank lending; interconnections; network centrality; spatial autoregressive models

The efficacy of a sumatriptan and naproxen combination pill in a patient with chronic migraines who discontinued triptan therapy in the past due to a self-reported poor response to sumatriptan monotherapy

A clinical decision report using: Mathew NT, Landy S, Stark S, et al. Fixed-dose sumatriptan and naproxen in poor responders to triptans with a short half-life. Headache. 2009;49(7):971-982. https://doi.org/10.1111/j.1526-4610.2009.01458.x for a patient with chronic migraines who had self-reported poor response to sumatriptan monotherapy

Colorful Gardens and Empowerment: Black Resistance and Self-Determination through Urban Farming

This thesis explores Black food justice organizations in Oakland and Detroit that tackle issues of food security in low income communities of color. I discuss how food deserts are a product of constant discrimination and marginalization perpetuated by racist laws and policies and explain how urban gardening helps Black people regain control of the food system and promotes empowerment and self-determination

Elliptic curves with a given number of points over finite fields

Given an elliptic curve $E$ and a positive integer $N$, we consider the problem of counting the number of primes $p$ for which the reduction of $E$ modulo $p$ possesses exactly $N$ points over $\mathbb F_p$. On average (over a family of elliptic curves), we show bounds that are significantly better than what is trivially obtained by the Hasse bound. Under some additional hypotheses, including a conjecture concerning the short interval distribution of primes in arithmetic progressions, we obtain an asymptotic formula for the average.Comment: A mistake was discovered in the derivation of the product formula for K(N). The included corrigendum corrects this mistake. All page numbers in the corrigendum refer to the journal version of the manuscrip