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Diane Ravitch, such an unbiased source. Lets assume the counterfactual - that teacher performance has no measurable effect. The logical conclusion is that since

Diane Ravitch, such an unbiased source. Lets assume the counterfactual - that teacher performance has no measurable effect. The logical conclusion is that since quality is irrelevant, we should focus on cost. I assume that you support this conclusion? Diane Ravitch certainly doesn't. The bulk of your notes show simply that variance is high, that the effect of teachers fades over time, and that the effect of teachers is small. None of this implies VAM doesn't work. Many of your sources don't even agree with you. For instance, the Mathematica evaluation suggests a 74% accuracy rate! Some years back I recall we discussed this, and I suggested you go learn about the difference between variance and bias. Have you done this? Incidentally, you do bring up yet another solid scientific conclusion that cuts against non-conservative ideologies: teachers don't matter much at all.

Alex3917 10y ago
> The bulk of your notes show simply that variance is high There is a lot in there about bias also, that's what all the stuff about standardized tests not being on an interval scale is about. Gifted vs mainstream vs special ed students show wildly different rates of progress on standardized tests that's completely divorced from how much they're actually learning, which means that the scores of teachers are largely determined by which populations they're teaching. > None of this implies VAM doesn't work. High variance absolutely implies that VAM doesn't work. If you are firing good teachers at random then only morons would go into teaching, especially given the barrier to entry. > the Mathematica evaluation suggests a 74% accuracy rate! In this context, 74% accurate means 100% useless for the above reason. > another solid scientific conclusion that cuts against non-conservative ideologies: teachers don't matter much at all. I would say that most of the research using standardized tests to 'prove' that teachers matter is wrong, but that's not the same as proving that teachers don't matter. Any research purporting to 'prove' that teachers don't matter is going to be flawed for the same reason, because you can't reliably measure teacher quality by using tests meant to evaluate students.
- yummyfajitas 10y ago
  High variance absolutely implies that VAM doesn't work. If you are firing good teachers at random then only morons would go into teaching. So only a moron would trade stocks, speculate on real estate, or take a job as a salesman? Of course, we just agreed that even if this is true, it doesn't matter. Morons are nearly as good at teaching as anyone else, and the results of good teaching fades over time anyway. So what would be the harm? It's a simple fact of statistics - the bigger the effect size, the easier it is to measure. It's simply innumeracy to claim large effects sizes and also impossibility to measure them. Why all the left wing mathematics denialism? (Another example of left wing mathematics denialism applies to the pigeon hole principle. If you have N houses and K > N people, K - N people won't have a house.)
  - Alex3917 10y ago
    > So only a moron would trade stocks, speculate on real estate, or take a job as a salesman? All of those are examples of jobs with fairly to extremely reliable performance measurements... E.g. if a salesperson sells makes 20 sales in a quarter, then there is zero chance of them getting fired because their managers think they actually made -7 sales. > Morons are nearly as good at teaching as anyone else, and the results of good teaching fades over time anyway. Again, not accurate. The evidence that good teachers have some magical impact on student performance as measured by standardized test scores is flawed, but that doesn't have any relevance to the question of whether or not good/bad teachers exist in reality. And in fact, if you buy into the idea that "education isn't the filling of a vessel, but the lighting of a fire," then you'd expect the impact of good teachers to become larger over time. (But again, not as measured by VAM.)
    - yummyfajitas 10y ago
      All of those are examples of jobs with fairly to extremely reliable performance measurements... E.g. if a salesperson sells makes 20 sales in a quarter, then there is zero chance of them getting fired because their managers think they actually made -7 sales. Whoah, suddenly you are applying a much lower level of skepticism to performance measurements now that we aren't talking about education. As you know, the mean standardized test score of students in a class (with no attempt to adjust for student quality) is just as objectively known as the number of sales. So I guess if we just did that, we'd be fine? Of course, the relevant question is how does that compare to a baseline # of sales that this salesperson could be expected to get? I knew a salesgirl doing enterprise software. In a given month she might make 0 sales, or 1, in a very good month 2. Is she a bad salesgirl because she had a month with 0 sales? That's variance, which according to you 100% invalidates a performance metric. You are making isolated demands for rigour in education that you don't seem to apply elsewhere. See this article for a description of this fallacy: http://slatestarcodex.com/2014/08/14/beware-isolated-demands-for-rigor/ http://slatestarcodex.com/2014/08/14/beware-isolated-demands... Now ask yourself, why are you doing this? Since you seem to believe good teachers exist, what evidence do you have of this? The lighting of fires in the belly of invisible dragons? http://www.godlessgeeks.com/LINKS/Dragon.htm http://www.godlessgeeks.com/LINKS/Dragon.htm
deleted 10y ago
[deleted]

Alex3917 10y ago

> The bulk of your notes show simply that variance is high There is a lot in there about bias also, that's what all the stuff about standardized tests not being on an interval scale is about. Gifted vs mainstream vs special ed students show wildly different rates of progress on standardized tests that's completely divorced from how much they're actually learning, which means that the scores of teachers are largely determined by which populations they're teaching. > None of this implies VAM doesn't work. High variance absolutely implies that VAM doesn't work. If you are firing good teachers at random then only morons would go into teaching, especially given the barrier to entry. > the Mathematica evaluation suggests a 74% accuracy rate! In this context, 74% accurate means 100% useless for the above reason. > another solid scientific conclusion that cuts against non-conservative ideologies: teachers don't matter much at all. I would say that most of the research using standardized tests to 'prove' that teachers matter is wrong, but that's not the same as proving that teachers don't matter. Any research purporting to 'prove' that teachers don't matter is going to be flawed for the same reason, because you can't reliably measure teacher quality by using tests meant to evaluate students.

yummyfajitas 10y ago
High variance absolutely implies that VAM doesn't work. If you are firing good teachers at random then only morons would go into teaching. So only a moron would trade stocks, speculate on real estate, or take a job as a salesman? Of course, we just agreed that even if this is true, it doesn't matter. Morons are nearly as good at teaching as anyone else, and the results of good teaching fades over time anyway. So what would be the harm? It's a simple fact of statistics - the bigger the effect size, the easier it is to measure. It's simply innumeracy to claim large effects sizes and also impossibility to measure them. Why all the left wing mathematics denialism? (Another example of left wing mathematics denialism applies to the pigeon hole principle. If you have N houses and K > N people, K - N people won't have a house.)
- Alex3917 10y ago
  > So only a moron would trade stocks, speculate on real estate, or take a job as a salesman? All of those are examples of jobs with fairly to extremely reliable performance measurements... E.g. if a salesperson sells makes 20 sales in a quarter, then there is zero chance of them getting fired because their managers think they actually made -7 sales. > Morons are nearly as good at teaching as anyone else, and the results of good teaching fades over time anyway. Again, not accurate. The evidence that good teachers have some magical impact on student performance as measured by standardized test scores is flawed, but that doesn't have any relevance to the question of whether or not good/bad teachers exist in reality. And in fact, if you buy into the idea that "education isn't the filling of a vessel, but the lighting of a fire," then you'd expect the impact of good teachers to become larger over time. (But again, not as measured by VAM.)
  - yummyfajitas 10y ago
    All of those are examples of jobs with fairly to extremely reliable performance measurements... E.g. if a salesperson sells makes 20 sales in a quarter, then there is zero chance of them getting fired because their managers think they actually made -7 sales. Whoah, suddenly you are applying a much lower level of skepticism to performance measurements now that we aren't talking about education. As you know, the mean standardized test score of students in a class (with no attempt to adjust for student quality) is just as objectively known as the number of sales. So I guess if we just did that, we'd be fine? Of course, the relevant question is how does that compare to a baseline # of sales that this salesperson could be expected to get? I knew a salesgirl doing enterprise software. In a given month she might make 0 sales, or 1, in a very good month 2. Is she a bad salesgirl because she had a month with 0 sales? That's variance, which according to you 100% invalidates a performance metric. You are making isolated demands for rigour in education that you don't seem to apply elsewhere. See this article for a description of this fallacy: http://slatestarcodex.com/2014/08/14/beware-isolated-demands-for-rigor/ http://slatestarcodex.com/2014/08/14/beware-isolated-demands... Now ask yourself, why are you doing this? Since you seem to believe good teachers exist, what evidence do you have of this? The lighting of fires in the belly of invisible dragons? http://www.godlessgeeks.com/LINKS/Dragon.htm http://www.godlessgeeks.com/LINKS/Dragon.htm

deleted 10y ago

[deleted]