Do certified mail third-wave follow-ups really boost response rates and quality?

The Total Design Method (TDM) of designing and implementing mail surveys has been shown to achieve high response rates. One key step in the TDM is sending a third-wave of surveys by certified mail. However, little research exists to verify the effectiveness of this step in improving response rates and quality relative to its increased expense, although this is the 50th anniversary of certified mail in the U.S. Perhaps as a result, scholars rarely use certified mail third-waves or omit third-wave mailings altogether. This article presents the results of two experiments that we embedded in two large-scale organizational mail surveys. Both studies reveal that sending a third-wave of questionnaires significantly increases the rate of response over the first two waves of mailings. Also, the results of Study 1 show that sending a certified mail third-wave has no appreciable effect on response quality. Study 2 shows that a certified mail third-wave does not significantly increase response rate or quality compared to sending the third-wave by regular, 1st-class mail.