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.)
The risk vs. reward profile for these jobs is very different. A stock trader can be successful one year and make up for losses the next, so long as he is successful more often than not. If an excellent teacher has a 25% chance of being fired every evaluation session, he has nothing to compensate for this risk -- just low pay, unconscionable hours, and a very difficult, thankless job.
Most teachers are teachers because of belief in helping children and personal dedication. Flipping a coin and saying "you're fired if I get two heads in a row" every year means that is gone.
It is not innumeracy to suggest there are so many confounding variables that are nearly impossible to separate from the treatment that it isn't a realistic or effective method for making real decisions about performance that negatively impact the careers and lives of dedicated public servants. It is innumeracy to suggest that "the bigger the effect size, the easier it is to measure" -- it is not incorrect technically, but it is very misleading. No matter how large the effect size, it can be very difficult to separate the effect of different variables with limited data (which is always the case -- we are testing one teacher against another)
Granted, I haven't read those particular sources and I'm not sure if this is the approach they take.
Of course phrases like "left wing mathematics denialism" are purposefully incendiary, contentless, and laughably absurd -- they belong somewhere like Breitbart, not here. Most Mathematicians are left-wing, for the record. I've never heard of anyone denying the pigeon hole principle in that context (or any context), but straw men are a very effective rhetorical device.
A stock trader can be successful one year and make up for losses the next, so long as he is successful more often than not
If you don't get good returns your first couple of years, you'll likely be out permanently. A couple of bad years on a 20 year trading record, you might be fine.
Then again, Alex's sources all note that VAM stabilizes after a number of years (between 3 and 5). So long term teachers should be fine too.
Similarly for salespeople. Like it or not, getting a professional evaluation based on a noisy objective measurement is nothing special. It happens in many professions - why should teachers be protected?
Also, I didn't realize 38.5 hours/week, 9 months/year was "unconscionable".
No good teacher only works 38.5 hours a week. They will often be awake at 1AM several nights a week grading papers and tests, they are expected to stay past contract time to meet with students, and they have significant continuing education requirements. Many also need to take on extracurricular activities or summer teaching to get enough money to live within 30 minutes of work.
Teaching is absolutely a thankless job in the actual work. Students are constantly disrupting class, calling teachers names, threatening teachers and other students. Administrators blame teachers for their students' behavior. Parents routinely shout at, insult, and threaten teachers. Other teachers are often hostile. Any perceived glory in teaching is just whitewashing the real nature of the job (kind of like military service -- lots of talk about glory and honor, but immense disrespect in day to day experiences).
"Dedicated public servants" is almost a pejorative euphemism at this point.
Then a significant majority of teachers are not "good", by your definition.
Some simple arithmetic: given that teachers are excluded from that study if they work less than 35 hours, we discover at most (38.5-35)/(K-35) % of teachers work K hours/week. (This is based on the extreme case of x% of teachers working K hours, 1-x% working 35 hours.) So if 50 hours/week is "good", then at most 23% of teachers are good.
As for your subjective opinions about "thankless", what evidence - if any - would cause you to change your belief?
How did they define and report "work", and are they including breaks in those averages?
I know several teachers. The burden of proof would be on you to demonstrate that teaching is a higher status profession with endlessly respectful and eager students.
When I was doing my student teaching for my teacher certification I would spend 90-100 hours a week either in a classroom, planning, grading, or doing coursework for my student teaching. It was unlikely to be any different for my first 5 years as a teacher had I gone into the profession. I make about twice as much now as I would have if I'd gone into teaching, and my work weeks now are more like 50-60 hours.
Saying that contract hours are the actual hours a teacher works is at best disingenuous. It's absolute bullshit.
The source I cited is not measuring contract hours. It's based on time diaries of work performed "yesterday". Why don't you try reading it before criticizing it?
Most likely you are simply mistaken/lying about the amount of hours you worked. Don't worry - you are in good company. Most people routinely give high numbers for how much they work "usually", as compared to how much they worked last week.
> 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.)
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.
Teachers aren't ranked based on mean test scores, they're ranked based on their estimated contribution to student test scores.
There are two issues here: 1) How accurate are the metrics 2) how stable are the metrics over time.
Here are the differences between sales and teaching:
- With VAM, not only do you have stability to worry about, but you also have the question of whether or not VAM is an accurate measure of teacher contribution to student performance in the first place. With sales you might argue that the number of sales or total contribution metrics don't accurately predict CLV or something, but the ambiguity there is trivial compared with VAM.
- With respect to stability, with teaching you only get test scores once a year, which means that it takes about five years until the VAM scores of teachers become relatively stable. Whereas with sales people, you get new metrics every quarter.
- Since what matters the most in business is having enough cashflow to stay in business, the short term view matters more than the longterm view. Whereas with students, what they achieve five and ten years out is much more important than how they perform at the end of each year.
- With sales, there is zero barrier to entry, and if you get fired then you can just get another job two weeks later. With teaching you need to spend 2+ years and tens of thousands of dollars to get into the profession, and if you get fired then the best case scenario is that it takes an entire year to get another job. But often you're basically just banned from the profession.
- With sales you're also making several times more money than you would as a teacher.
If teachers were estimated on mean test scores, we could rank them the same way we often rank salespeople. Would you be ok with this? If not, why not?
And more importantly, why don't your newfound rationalizations apply equally well to salespeople or traders?
(Incidentally, traders also are measured against a statistical model - risk adjustments + benchmark rate.)
VAM is an accurate measure of teacher contribution to student performance in the first place.
And with sales, you need to determine whether your attribution/commission model is an accurate measure of salesperson compensation to company profits. It's the exact same problem, it uses similar statistical methods, and it has variance.
* Whereas with sales people, you get new metrics every quarter.*
So test every quarter and evaluate on that basis. Done. Further, many salespeople have less information per month than teachers - for example, the enterprise salesgirl I mentioned earlier who has 0, 1 or 2 sales/month.
You seem to be desperately reaching for rationalizations that explain why teaching is fundamentally different than every other profession. Why is that?
> If teachers were estimated on mean test scores, we could rank them the same way we often rank salespeople.
Good sales people create value by bringing in money, and sales are measured in money. Good teachers create value by teaching well, and mean test scores don't measure teaching well. That might be slightly simplistic, but that's the big picture idea.
> And with sales, you need to determine whether your attribution/commission model is an accurate measure of salesperson compensation to company profits
I'm not arguing that sales people are always fairly compensated, only that there is less complexity in doing so and the epistemological issues are more straightforward.
> So test every quarter and evaluate on that basis.
In sales, measuring is free, whereas testing is more like growing carrots... If you keep pulling up your carrots to check how big they are, then at the end of the summer you're not going to have any carrots.
> explain why teaching is fundamentally different than every other profession
So near as I can tell, we can't detect the dragon by looking since he's invisible. We can't use a heat meter to detect him with since the fire lives in his (perfect insulator) stomach. We can't put dust on the floor to look for fingerprints since he floats.
Would the world be any different if the dragon didn't exist?
Similarly, if "teaching well" didn't exist, how would the world be different? What testable predictions (if any) does your set of ideas make?
In sales, measuring is free, whereas testing is more like growing carrots... If you keep pulling up your carrots to check how big they are, then at the end of the summer you're not going to have any carrots.
Giving quarterly exams will somehow destroy all learning?
This goes against pretty much all the principles of spaced repetition. I take a Hindi test every day and it sure seems to help me.
I mean if you're willing to accept that the best teachers are the ones that improve standardized tests the most then the research on VAM shows that good and bad teachers exist, it's just not able to reliably differentiate between them in a reasonable amount of time.
A more straightforward 'proof' would just be looking at all students who take a class on something random like mycology and then seeing what percentage have had some level of engagement with that subject five or ten years later.
...teaching is fundamentally different than every other profession. Why is that?
The payoff of a good teacher shows up years down the road, not once per quarter. Teaching is extremely politicized; parents and random joes like to manipulate the system and are likewise manipulable by less scrupulous members of the public with a hidden agenda -- this is the "think of the children" phenomenon writ large. Teacher class assignments are politically motivated, not random, so student quality is not random. There are substantial movements by parents to eliminate standardized tests because they don't want their children labeled or profiled, and yet you want to increase testing to every quarter. The fears of those parents are somewhat justified because testing software keeps all kinds of behavioral metrics on students that are never revealed to parents. You have an insanely powerful union to deal with that doesn't necessarily represent the true interests of teachers.
One problem with standardized tests in my region is that teachers are not allowed to count them on grades, so students will just walk into the testing center, click "A" 150 times, and stare blankly for the rest of the time. That's hardly a reflection on teacher quality.
Student quality (and administrative or support staff manipulation of student-to-teacher assignments) varies a lot from teacher to teacher and year to year, probably much more than teacher quality. You talk about using quantitative measurements, but then treat variance like a qualitative thing that is equally ignorable regardless of scope.
>(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.)
Can't win an argument because the facts aren't on your side? Bring up a red herring for a random insult! Why all the talk of left wing mathematics denialism? This is a perfect example of $GROUP_I_DISAGREE_WITH's typical meaningless sophistry!!
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.)