I wondered if you had an effect size for assessment capable learners? This is something my colleagues and I have been discussing and I found an article that quotes you but it did not include an effect size.

One of my missions is to work above the data (but, if I must, the effect size for assessment capable learners is 1.33) – and the notion of assessment capable students (or self-reported grades) is a higher order concept aiming to unite many critical influences – like student assessment of their work, teacher clarity, use of thinking strategies and others as we discussed in the 2009 book. Indeed, it might even be hard to find studies on this polymorphous notion of ‘assessment capable learners,’ and it is the story we weave in ‘assessment capable learners’ that matters” (John Hattie, personal communication, December 30, 2018).