I think the error is not just that they generalised incorrectly, but that they didn’t know enough to be justified in doing so. So it combines overconfidence and over/misgeneralising.
The word ‘sophomoric’ includes some of the right connotations. One definition says ‘Overconfident but immature or poorly informed’.
So though ‘sophomoric’ is not quite specific enough itself, maybe it could be used to make a new phrase eg ‘sophomoric bias’ or ‘sophomoric generalisation’.
I think the error is not just that they generalised incorrectly, but that they didn’t know enough to be justified in doing so. So it combines overconfidence and over/misgeneralising.
The word ‘sophomoric’ includes some of the right connotations. One definition says ‘Overconfident but immature or poorly informed’.
So though ‘sophomoric’ is not quite specific enough itself, maybe it could be used to make a new phrase eg ‘sophomoric bias’ or ‘sophomoric generalisation’.