It's not always the easiest reading in the world, and the formatting and structure often require a dive down a fairly deep rabbit hole of terminology, methodology, and sourcing. But it's fascinating stuff.
Additionally, the exposition is clear, the graphs are simple but effective, and its just wonderful in most respects.
The only (minor) criticism I would have is that I would have liked to have seen more of the input code (I didn't spot a link to it anywhere).
What do you mean by input code? If you mean the original R code, the entire analysis is provided in http://www.gwern.net/DNB%20meta-analysis#source - when I add new studies, all I do is add an entry to the table of data, re-run the R code, and then copy-paste the relevant output. (I could probably automate it even more with Knittr but it doesn't seem worth the work of integrating Knittr with Hakyll.)
So it would be helpful if you had some explanation of your final conclusion.
As it happens, the active-control-group studies seem to be converging on zero, so I don't even have to appeal to priors. But if the result had been to find, say, d=0.4, I still wouldn't believe it: it would be more likely that the IQ tests are being corrupted, or publication bias had caused this, or fraud was involved, than we would have found a simple WM exercise which genuinely increased IQ after countless failures.
I do, of course, want to finish up the details (correct the Clouter data, and include the Seidler et al 2010 and Colom et al 2013 data) before I write up any kind of definitive conclusion & do a post-mortem of dual n-back.
I wonder if a Dual N-Back task that was based on material-to-be-memorized, rather than just positions/letters, would have interesting effects on working or long-term memory. (You'd be stressing two related/entangled recall systems at once.)
Anyone done that test?
I would be fascinated to hear how it went.
"Brain Workshop is a free open-source version of the dual n-back brain training exercise."
As to how valuable WM is, I'm not sure. There were a bunch of positive papers from people like Klingberg, but these tend to use subjective measures or WM-related measures, and there seems to be an absence of studies tying the WM training to concrete useful changes like improved grades or standardized exam scores.