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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

Can use of the word difference help communication scholars to rethink communication with equity central, with the politics of difference at its center, or, in other words, where a deviation from an assumed norm is embraced as an intrinsic and valued part of the process of change making? Does adopting the words difference and equity in lieu of tolerance, diversity, and multiculturalism help bring us to a place where racialized minorities are not just window dressing, the tokens that stave off allegations of racism? In this essay, I briefly trace various discourses surrounding tolerance, multiculturalism, and diversity, before moving to difference to think to equity. Linguistic change coincides with and can foment historical and political change, yet we do not need more or different words: We need more equitable universities. Interrogating the language around this potentially change-making word uncovers, in the words of Herman Gray, a politics of difference that is unutterable without demands for equity.