PROMPTING TECHNIQUES TO INCREASE THE RETURN RATE OF MAILED QUESTIONNAIRES 1

To increase the return rate of questionnaires mailed to clergy and physicians concerning their mental‐health practices, different prompts were used after the questionnaire was received during four mail‐outs to four randomly drawn samples of clergy and physicians. For each mail‐out, the sample was divided into experimental (received prompt) and comparison (no prompt) groups, and one type of prompt or combination was used. Non‐returnees of the questionnaire in the experimental group received either: (a) a single telephone call, (b) a memo, (c) a package (personal letter and new questionnaire) or package plus a telephone call, or (d) a double call. Comparison physicians and clergy were mailed only the original questionnaire. Relative to their respective comparison group's return rate, which averaged 22% across the four mail‐outs (range 18% to 24%), the single call and package alone about doubled the overall return rate, the package and call increased the return rate about two‐and‐a‐half fold, and the double call almost tripled the return rate. The memo was ineffective. A cost‐effectiveness analysis indicated that the double‐call procedure was less expensive than the single call, and much less expensive than the package alone or package with a call in securing returns. An analysis of the pattern of returns showed clearly that when prompts were not delivered (comparison groups), very few returns were received after about seven days from the initial mail‐out. Most returns from prompts (experimental groups) were received by several days after the prompt. The results were seen as salient to the problem of reducing selection or volunteer bias in questionnaire studies and subsequent research demonstrating the effectiveness of telephone calls made about a week after distribution of surveys in securing high return rates was discussed.