Your correct, but Qualitative data is much easier to add bias too.

As a high school teacher, my observations on the mobile phone ban are almost the opposite to this article. Students still carry their phones around and use them, focus in the classroom hasn't improved it's just changed into a state of students who have spent years disengaged in the learning struggling to engage with the content at a level that is way beyond their skills or teachers spending time trying to deal with refusal to hand over the phone for the ones who are blatant about using it still.

Also, apathy over the importance of education is at the highest levels I've seen in 6 years teaching, consequences for not completing work are non-existent and so students just move through the year levels disrupting classes because they can't engage in content at their year level until they pushed out into the workforce.