Question 4: assessment tools
Our final research question focused on the impact of assessment tools on examining intervention effects, In addition to learning transfer, how reading and reading-related skills are measured in intervention studies can have a considerable impact on the conclusions. This is also important in our findings. When analysing the letter-sound knowledge task at the level of the individual letter, we find intervention-related gains which were not captured using aggregated data from the same task, which would arguably correspond to a conventional pen-and-paper assessment. In the case of letter-sound knowledge for example, pen-and-paper tests are typically administered without time pressure and reach ceiling within the first few months of school (