Only in Sweden, in reading literacy, can a major change in results be observed, which might be related to the amount of time students spend on the Internet. Even if it is not possible to clearly show whether the change of test mode in PISA 2015 has influenced the results, the authors warn that there are reasons to be careful when comparisons are made of PISA results from 2015 with results from earlier PISA studies. The comparative link between the PISA studies from different years might be weaker in 2015 than earlier.