The study is interesting and included data from nearly 58,000 children, providing a representative and extensive sample. However, I find some biases, not in relation to the methodology, but in the approach.

It's important to understand that correlation does not imply causality. At these ages, what we know so far is that the issue does not lie with screens but rather in removing the stimuli that babies need at these ages, whether it's due to technology or other factors. From my point of view, the key takeaway from the study, as the study itself indicates, is to highlight the importance of social interaction for the development of children.

Furthermore, the study indicates that it does not include children diagnosed with ASD (autism, pervasive developmental disorder, and Asperger's syndrome). It's important to note that some diagnoses of this kind cannot be made before the age of 2 because sometimes it's unclear whether certain observed aspects refer to a developmental delay in the child, so many of the diagnoses are confirmed or ruled out during the Early Childhood Education stage, between the ages of 3 and 6. Considering that the study analyzes up to the age of 3, this could be a bias to take into account. Therefore, there may be other factors associated with child development that were not considered.

The study only assessed television and DVDs but did not include the use of tablets and phones.

The data are collected by families, and specifically, the role of the mother is crucial in this study. The questionnaires included questions about children's TV/DVD screen time and their developmental performance. It might have been interesting if the performance analysis had been validated by pediatricians or experts in children's developmental psychology. It's not that this fact diminishes the value of the work, but data collected by families can introduce biases into the assessments they make of their children.

For all these reasons, I find it risky to assert that screen time causes developmental problems. It's a descriptive and observational study, and it did not evaluate the type of content or the context in which screens are used. I think it's interesting and valuable, but the approach to interpreting the results should be adjusted accordingly.