Finally, I was able to go through the new version of Visible Learning for the first time and:

• It’s again an enormous piece of work, but…
• I’m also left a little hungry, and
• I see a great danger popping up again and a new danger emerging.

First, the good:

• Hattie addresses the various commentaries and critiques of his work and meta-analysis as a method and source in general.
• He has tried to make it a more coherent work rather than listing insights from meta-analyses.

But then the lesser:

• the work is even more comprehensive and, at the same time, often more superficial than the original 2008 work. There is interpretation, but often briefer.
• The element of time and location in which a study happened is mentioned, but…

The latter brings the first danger I see: for example, who will read that the seemingly highly effective “constructive teaching” is based on only 3 Turkish meta-analyses. These meta-analyses also broadly define the concept and are mainly based on Turkish studies. This example was passed on to me by Tim Surma earlier this week and is, in my opinion, a valid example.

Or what about the relatively low effect of co-or team-teaching that Hattie reports, but where you also have to read that there are hardly any quality studies (something we also found when writing the second Urban Myths book). More importantly, the reasons for co-teaching or team teaching and the forms of such teaching can be quite different, making general statements quite difficult to make.

I found many such examples while reading. Thus, if you only look at the charts’ new style, you return from a barren and ill-informed journey. Sometimes what Hattie reports is an example of a (large or limited) correlation; sometimes, it is an effective approach. But a .50 at one lemma thus does not necessarily correspond to the .50 of another.

In his place, I would have been more critical and not included certain lemmas because the knowledge base seems outdated or limited or uses unclear definitions (something he regularly returns to).
The new danger is that because Hattie tries to make the narrative more coherent and the book did become more personal in style, the book also becomes more of a promotion of his own model. Just as any model can never be beatific, the amount of meta-analysis can make it seem that way.
It is still a good “phone book”, which, according to Hattie, maybe the last update in the form of a book. The huge proliferation of meta-analyses may make writing another update in this way impossible. Hattie suspects a more wiki-like approach in the future, perhaps by others.