All students touched upon reasons why we might have seen such broad variability in response to the question "are you familiar with the digital divide?"  Might this be an example of "measurement error" which could be caused by "random" or "systematic" reasons. In this case, it is likely due to the fact that the response groups are so different. Read the following link and offer your thoughts as to whether you think the differences in response are due to random or systematic issues as your are able.  http://www.socialresearchmethods.net/kb/measerr.php