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We present a new estimator for causal effects with panel data that builds on insights behind the widely used difference-in-differences and synthetic control methods. Relative to these methods we find, both theoretically and empirically, that this "synthetic difference-in-differences" estimator has desirable robustness properties, and that it performs well in settings where the conventional estimators are commonly used in practice. We study the asymptotic behavior of the estimator when the systematic part of the outcome model includes latent unit factors interacted with latent time factors, and we present conditions for consistency and asymptotic normality. (JEL C23, H25, H71, I18, L66)

AbstractWe develop front‐door difference‐in‐differences estimators as an extension of front‐door estimators. Under one‐sided noncompliance, an exclusion restriction, and assumptions analogous to parallel trends assumptions, this extension allows identification when the front‐door criterion does not hold. Even if the assumptions are relaxed, we show that the front‐door and front‐door difference‐in‐differences estimators may be combined to form bounds. Finally, we show that under one‐sided noncompliance, these techniques do not require the use of control units. We illustrate these points with an application to a job training study and with an application to Florida's early in‐person voting program. For the job training study, we show that these techniques can recover an experimental benchmark. For the Florida program, we find some evidence that early in‐person voting had small positive effects on turnout in 2008. This provides a counterpoint to recent claims that early voting had a negative effect on turnout in 2008.

Purpose
This paper aims to present the Difference-in-Differences (DiD) method in an accessible language to a broad research audience from a variety of management-related fields.


Design/methodology/approach
The paper describes the DiD method, starting with an intuitive explanation, goes through the main assumptions and the regression specification and covers the use of several robustness methods. Recurrent examples from the literature are used to illustrate the different concepts.


Findings
By providing an overview of the method, the authors cover the main issues involved when conducting DiD studies, including the fundamentals as well as some recent developments.


Originality/value
The paper can hopefully be of value to a broad range of management scholars interested in applying impact evaluation methods.

Ben Fine's food system (see abstract in this section of SA 43:5) is examined in relation to other systems. The distinguishing feature of food provision systems is their dependence on both the organic & the inorganic, with the organic properties of food influencing interaction between structures & tendencies. Fine points to a link between the household & agriculture as key, yet this argument is weakened through unclear discussion of: agriculture as defined by biology; vertical provisioning; the concept of "organic"; & the question of consumption. Although Fine's discussion provides imortant points for departure in a political economy of food, neither the organic nor cultural factors are taken seriously enough, leaving understanding of food provisioning systems not yet attained. 16 References. A. Cole

I challenge the age-old binary opposition between human and animal, not as philosophers sometimes do by claiming that humans are also animals, or that animals are capable of suffering or intelligence, but rather by questioning the very category of "the animal" itself. This category groups a nearly infinite variety of living beings into one concept measured in terms of humans—animals are those creatures that are not human. In addition, I argue that the binary opposition between human and animal is intimately linked to the binary opposition between man and woman. Furthermore, I suggest that thinking through animal differences or differences among various living creatures opens up the possibility of thinking beyond the dualist notion of sexual difference and enables thinking toward a multiplicity of sexual differences.