"Truths" devoid of empirical proof: underlying assumptions surrounding value-added models in teacher evaluation

Despite the overwhelming and research-based concerns regarding value-added models (VAMs), VAM advocates, policymakers, and supporters continue to hold strong to VAMs’ purported, yet still largely theoretical strengths and potentials. Those advancing VAMs have, more or less, adopted and promoted a set of agreed-upon, albeit “heroic” set of assumptions, without independent, peer-reviewed research in support. These “heroic” assumptions transcend promotional, policy, media, and research-based pieces, but they have never been fully investigated, explicated, or made explicit as a set or whole. These assumptions, though often violated, are often ignored in order to promote VAM adoption and use, and also to sell for-profits’ and sometimes non-profits’ VAM-based systems to states and districts. The purpose of this study was to make obvious the assumptions that have been made within the VAM narrative and that, accordingly, have often been accepted without challenge. Ultimately, sources for this study included 470 distinctly different written pieces, from both traditional and non-traditional sources. The results of this analysis suggest that the preponderance of sources propagating unfounded assertions are fostering a sort of VAM echo chamber that seems impenetrable by even the most rigorous and trustworthy empirical evidence.