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The external validity of treatment effects: an investigation of educational production

Includes bibliographical references.

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Bibliographic Details
Main Author: Muller, Sean Mfundza
Other Authors: Wittenberg, Martin
Format: Thesis
Language:English
Published: School of Economics 2015
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access_status_str Open Access
author Muller, Sean Mfundza
author2 Wittenberg, Martin
author_browse Muller, Sean Mfundza
Wittenberg, Martin
author_facet Wittenberg, Martin
Muller, Sean Mfundza
author_sort Muller, Sean Mfundza
collection Thesis
description Includes bibliographical references.
format Thesis
id oai:open.uct.ac.za:11427/13324
institution University of Cape Town (South Africa)
language eng
last_indexed 2026-06-10T12:31:53.390Z
license_str Not specified — see source repository
provenance_str_mv Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository
publishDate 2015
publishDateRange 2015
publishDateSort 2015
publisher School of Economics
publisherStr School of Economics
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source_str UCTD — University of Cape Town Open Access Repository
spelling oai:open.uct.ac.za:11427/13324 The external validity of treatment effects: an investigation of educational production Muller, Sean Mfundza Wittenberg, Martin Economics Includes bibliographical references. The thesis begins, in chapter 1, with an overview of recent debates concerning the merits of randomised programme evaluations and a detailed review of the literature on the extrapolation of treatment effects ('external validity'). Building on the insights of Cook and Campbell (1979) and a result by Hotz, Imbens, and Mortimer (2005), I then argue that the fundamental challenge to external validity may be interactive relationships between the treatment variable and other covariates. The empirical relevance of this claim is developed through two contributions to the economics of education literature, using data from the Tennessee class size experiment known as 'Project STAR'. Chapter 2 contributes to the literature on teacher quality, describing and implementing a novel method for constructing a value-added quality measure that uses a single cross-section of data in which students and teachers are randomly assigned to different-sized classes. The core insight is that constructing the value-added measure within treatment categories creates a plausible measure of quality that is simultaneously independent of treatment. The analysis of chapter 3 concerns the literature on class size effects. I argue that the effect of class size on educational achievement may be dependent on other class-level factors and that this should be considered when estimating educational production functions. Using the variable constructed in chapter 2, I estimate interaction effects between class size and teacher quality and find a number of statistically and economically significant effects. Specifically, higher quality teachers are associated with more beneficial effects of smaller classes. Those results suggest a possible unification of the class size and teacher quality literatures, with the policy problem being one of finding an optimal combination of these two factors. The broader contribution, further to the analysis of chapter 1, is to illustrate an obstacle to external validity: class size effects are unlikely to be the same across contexts where the teacher quality distribution differs. The experimental estimation of class size effects therefore serves as an empirical case study of the challenges to external validity that arise from interaction. 2015-07-03T08:26:53Z 2015-07-03T08:26:53Z 2014 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/13324 eng application/pdf School of Economics Faculty of Commerce University of Cape Town
spellingShingle Economics
Muller, Sean Mfundza
The external validity of treatment effects: an investigation of educational production
thesis_degree_str Doctoral
title The external validity of treatment effects: an investigation of educational production
title_full The external validity of treatment effects: an investigation of educational production
title_fullStr The external validity of treatment effects: an investigation of educational production
title_full_unstemmed The external validity of treatment effects: an investigation of educational production
title_short The external validity of treatment effects: an investigation of educational production
title_sort external validity of treatment effects an investigation of educational production
topic Economics
url http://hdl.handle.net/11427/13324
work_keys_str_mv AT mullerseanmfundza theexternalvalidityoftreatmenteffectsaninvestigationofeducationalproduction
AT mullerseanmfundza externalvalidityoftreatmenteffectsaninvestigationofeducationalproduction