No of course not, would be my first response. However researchers from Bristol seem to disagree, as can be read in an article on the BBC website "Left-handers' lower test scores". In the article researchers seem to conclude that the lower scores obtained by left-handers and mixed-handers mean they are more prone to cognitive developmental problems. They even advise that a test of 'handedness' is administered to guide early intervention strategies.
Now I haven't had a chance to examine this research, but on the face of it this seems a bit odd. As someone with a background in computer based assessment, I am very acutely aware of validity issues. When computers are used to assess, the question 'is this medium disadvantaging students' is asked very regularly (perhaps even somewhat too often). It strikes me that with our pen and paper based assessments, this question is not asked often enough.
Might it be that our traditional assessment system, that has a very high emphasis on writing skills, is disadvantaging students who are not naturally equip ed to deal well with our particular written tradition?
But even if my doubts are unfounded, is pre-emptive testing really the answer to this issue? Are we going to translate this statistical trend into something that is going to stigmatise individuals without them necessarily having any related difficulties? I think that is really taking things a bit too far.