American Statistical Association (ASA) Position Statement on VAMs
Inside my most recent post, about the Top 14 research-based articles about VAMs, there was a great research-based statement that was released just last week by the American Statistical Association (ASA), titled the “ASA Statement on Using Value-Added Models for Educational Assessment.”
It is short, accessible, easy to understand, and hard to dispute, so I wanted to be surenobody missed it as this is certainly a must read for all of you following this blog, not to mention everybody else dealing/working with VAMs and their related educational policies. Likewise, this represents the current, research-based evidence and thinking of probably 90% of the educational researchers and econometricians (still) conducting research in this area.
Again, the ASA is the best statistical organization in the U.S. and likely one of if not the best statistical associations in the world. Some of the most important parts of their statement, taken directly from their full statement as I see them, follow:
- VAMs are complex statistical models, and high-level statistical expertise is needed to
develop the models and [emphasis added] interpret their results. - Estimates from VAMs should always be accompanied by measures of precision and a discussion of the assumptions and possible limitations of the model. These limitations are particularly relevant if VAMs are used for high-stakes purposes.
- VAMs are generally based on standardized test scores, and do not directly measure
potential teacher contributions toward other student outcomes. - VAMs typically measure correlation, not causation: Effects – positive or negative –
attributed to a teacher may actually be caused by other factors that are not captured