We obtained the list of telephone numbers for the survey of parents from middle school
students at these schools. Researchers asked students for the names and telephone numbers of
their parents, and permission to call them to do the telephone survey. We asked for this
information from students who did not complete surveys as well as those who did complete
surveys. One important note regarding sample for telephone surveys is that it may privilege more
highly educated and affluent parents, as this population usually moves less often and has more
stable telephone numbers.