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The Irreconcilables


Fantastic response, I had a hard time with the report while reading it. TNTP has a point but, they truly are not clear. THe point , to me, is what will improve teacher retention,not attack those who stayed. We need more teachers and more teachers staying , making it a life long profession.

Beyond the statistical imprecision issue (although, they do have uncertainty estimates for District A and incorporate it into their "irreplaceable" algorithm), what I don't think is very clear from the report is that the thresholds for "exceptional" vary from district to district because the growth models aren't pooled (the got the estimates from the district, rather than running themselves, which is bizarre): so, teachers, after conditioning on some characteristics, are compared to other teachers within that district. So, the top 20% in one district may be quite different than the top 20% in another district. What's doubly bizarre is that they then used these disparate growth models to then standardize learning gains in terms of months of learning (footnote 4) without providing the formula they used to do this. Since the distribution and magnitude of these effects may differ by district, I can't see how this could mathematically or even substantively work. A standard deviation may be different in district A than in district B, so the learning gain yield must also be different. Right? They're also unclear about whether the 20% threshold was pre-determined (as it indicates in the Technical Appendix), or whether it was based on the distribution of teacher effect estimates from the growth models (as it suggests on page 2 with the phrase "fell into this category").

Thanks for posting, Matt. A quick question--I've just read the report, but have not gotten into the nitty gritty of measures. Are these teachers considered "irreplaceable" based on standardized test scores alone? Were any other measures used to determine this "top 20%"? How does TNTP suggest schools identify those "irreplaceable" teachers who work in non-testing subjects or areas? I found some valuable information in the report (i.e., appreciate good teachers, work to keep them, etc.) but admit I'm a bit concerned that this is a performance-pay-in-sheep's-clothes piece of policy work. Overblown concern, considering the players at the table?

Hi Jo, In the four regular public school districts, yes - they use only test-based productivity measures (growth or value-added models) to sort teachers. In their CMO sub-sample, they use full evaluation results, which (if I recall correctly) do not employ any test-based components. I'm afraid I cannot speak to the second question you pose, except to say that (and I'm generalizing here) TNTP tends to support performance-based pay, and I think they're quite open and honest about that position. Thanks for the comment, MD

You've made a crucial point because words matter, and this clear exaggeration may undercut the significance of retaining quality teachers in public schools. As somebody who left teaching high school in public schools after two years almost 27 years ago, I can also confirm that working conditions and pay matter. It's difficult to sustain one's own standards if you feel surrounded by hopelessness, mediocrity and student indifference.


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