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Relative Effectiveness of Personalized and Form Covering Letters in Initial and Follow-up Mail Surveys

Nonresponse is a serious threat to validity in mail surveys, prompting the need for research on techniques for increasing response rates. The relative effectiveness of personalized versus form covering letters in obtaining responses in a mail questionnaire survey was investigated for both initial and follow-up mailings. A questionnaire eliciting opinions about content in college courses in measurement was sent to 1000 Utah school teachers, randomly divided into two groups, with 500 receiving personalized letters and 500 receiving form letters. Nonrespondents in each group were randomly divided, with half receiving personalized follow-up letters and half receiving form follow-up letters. Using nondirectional hypothesis tests, no statistically significant differences were found in the relative effectiveness of personalized or form letters in either initial or follow-up mailings. These findings do not support the widely held belief that personalized covering letters improve response rates.