1.22 Sample with caution According to a recent survey conducted by the Pew Research Center, it was found that, in 2014, 82% of all American internet users between the ages of 18 to 29 used Facebook. Why is it not safe to infer anything from this survey about:

a. the proportion of the general population of all American internet users who use Facebook?

b. the proportion of the general population of Americans who use Facebook?