Pew Research compared respondents to an ordinary 5-day telephone survey with respondents to a 4-monthlong rigorous survey designed to generate the highest possible response rate. They were especially...

Pew Research compared respondents to an ordinary 5-day telephone survey with respondents to a 4-monthlong rigorous survey designed to generate the highest possible response rate. They were especially interested in identifying any variables for which those who responded to the ordinary survey were different from those who could be reached only by the rigorous survey.