Thursday, February 27, 2014

VAM for Dummies

If you don't spend every day with your head stuck in the reform toilet, receiving the never-ending education swirly that is school reformy stuff, there are terms that may not be entirely clear to you. One is VAM-- Value-Added Measure.

VAM is a concept borrowed from manufacturing. If I take one dollar's worth of sheet metal and turn it into a lovely planter that I can sell for ten dollars, I've added nine dollars of value to the metal.

It's a useful concept in manufacturing management. For instance, if my accounting tells me that it costs me ten dollars in labor to add five dollars of value to an object, I should plan my going-out-of-business sale today.

And a few years back, when we were all staring down the NCLB maw requiring that 100% of our students be above average by this year, it struck many people as a good idea-- let's check instead to see if teachers are making students better. Let's measure if teachers have added value to the individual student.

There are so many things wrong with this conceptually, starting with the idea that a student is like a piece of manufacturing material and continuing on through the reaffirmation of the school-is-a-factory model of education. But there are other problems as well.

1) Back in the manufacturing model, I knew how much value my piece of metal had before I started working my magic on it. We have no such information for students.

2) The piece of sheet metal, if it just sits there, will still be a piece of sheet metal. If anything, it will get rusty and less valuable. But a child, left to its own devices, will still get older, bigger, and smarter. A child will add value on its own, out of thin air. Almost like it was some living, breathing sentient being and not a piece of raw manufacturing material.

3) All piece of sheet metals are created equal. Any that are too not-equal get thrown in the hopper. On the assembly line, each piece of metal is as easy to add value to as the last. But here we have one more reformy idea predicated on the idea that children are pretty much identical.

How to solve these three big problems? Call the statisticians!

This is the point at which that horrifying formula that pops up in these discussion appears. Or actually, a version of it, because each state has its own special sauce when it comes to VAM. In Pennsylvania, our special VAM sauce is called PVAAS. I went to a state training session about PVAAS in 2009 and wrote about it for my regular newspaper gig. Here's what I said about how the formula works at the time:

PVAAS uses a thousand points of data to project the test results for students. This is a highly complex model that three well-paid consultants could not clearly explain to seven college-educated adults, but there were lots of bars and graphs, so you know it’s really good. I searched for a comparison and first tried “sophisticated guess;” the consultant quickly corrected me—“sophisticated prediction.” I tried again—was it like a weather report, developed by comparing thousands of instances of similar conditions to predict the probability of what will happen next? Yes, I was told. That was exactly right. This makes me feel much better about PVAAS, because weather reports are the height of perfect prediction.

Here's how it's supposed to work. The magic formula will factor in everything from your socio-economics through the trends over the past X years in your classroom, throw in your pre-testy thing if you like,  and will spit out a prediction of how Johnny would have done on the test in some neutral universe where nothing special happened to Johnny. Your job as a teacher is to get your real Johnny to do better on The Test than Alternate Universe Johnny would.

See? All that's required for VAM to work is believing that the state can accurately predict exactly how well your students would have done this year if you were an average teacher. How could anything possibly go wrong??

And it should be noted-- all of these issues occur in the process before we add refinements such as giving VAM scores based on students that the teacher doesn't even teach. There is no parallel for this in the original industrial VAM model, because nobody anywhere could imagine that it's not insanely ridiculous.

If you want to know more, the interwebs are full of material debunking this model, because nobody-- I mean nobody-- believes in it except politicians and corporate privateers. So you can look at anything from this nifty three minute video to the awesome blog Vamboozled by Audrey Amrein-Beardsley.

This is one more example of a feature of reformy stuff that is so top-to-bottom stupid that it's hard to understand. But whether you skim the surface, look at the philosophical basis, or dive into the math, VAM does not hold up. You may be among the people who feel like you don't quite get it, but let me reassure you-- when I titled this "VAM for Dummies," I wasn't talking about you. VAM is always and only for dummies; it's just that right now, the dummies are in charge.

1 comment:

  1. Thank you and looking for more posts; I enjoyed reading them, informative. Cheers!