Question 3: intervention properties
word reading fluency outcome
To answer the third research question, whether in-game metrics acquired from the training phase would be relevant predictors for training outcomes, we looked for possible associations between game exposure and response to intervention. Exposure measures potentially reflecting learning opportunity were the number of played sessions, played hours, played levels, seen items, given responses and the maximum game level reached by the end of the intervention. The separate inclusion of these six measures of game exposure and progress was tested in all models fitted for the seven outcomes mentioned above and in no case were they relevant predictor for intervention outcomes (see Results of Question 1: Response to intervention).As an additional explorative analysis, we focussed on the word reading fluency outcome, re-included children who played less than 20 sessions (