Online Medical Info USA Today posted this question on its website: “How often do you seek medical information online?” Of 1072 Internet users who chose to respond, 38% of them responded with...

Online Medical Info USA Today posted this question on its website: “How often do you seek medical information online?” Of 1072 Internet users who chose to respond, 38% of them responded with “frequently.” What term is used to describe this type of survey in which the people surveyed consist of those who decided to respond? What is wrong with this type of sampling method?