Evaluation of differences in giving and volunteering data collected by in-home and telephone interviewing

While preparing for its 1999 study, Giving and Volunteering in the United S tates, Independent Sector was told by its contractor that starting in 2000, it could no longer conduct the survey using in-home interviews. Independen t Sector contracted with another company to do a parallel study in 1999 by telephone to identify issues related to changing the survey mode. The resul ts showed highly statistically significant differences on many of the major questions, raising questions as to whether the differences were mainly due to between-company or between-collection modalities. Another company was t hen commissioned to do both an in-home study and a telephone study in two c ities in New England. With similar training for all interviewers, better sa mpling methods, prior letters to potential respondents, incentives, and mul tiple follow-ups, the results showed no significant differences between mod es on any of the major questions.