Robert Slavin just published this blog about problems with meta-analyses. He writes:

One of the best things about living in Baltimore is eating steamed hard shell crabs every summer.  They are cooked in a very spicy mix of spices, and with Maryland corn and Maryland beer, these define the very peak of existence for Marylanders.  (To be precise, the true culture of the crab also extends into Virginia, but does not really exist more than 20 miles inland from the bay).  

As every crab eater knows, a steamed crab comes with a lot of inedible shell and other inner furniture.  So you get perhaps an ounce of delicious meat for every pound of whole crab. Here is a bit of crab math.  Let’s say you have ten pounds of whole crabs, and I have 20 ounces of delicious crabmeat.  Who gets more to eat?  Obviously I do, because your ten pounds of crabs will only yield 10 ounces of meat. 

All Baltimoreans instinctively understand this from birth.  So why is this same principle not understood by so many meta-analysts?

For the rest of the blog clock on the pencils 🙂