Factors affecting response rates to natural resource - Focused mail surveys: Empirical evidence of declining rates over time

We analyzed factors that could affect response rates for 105 mail surveys conducted by the Human Dimensions Research Unit at Cornell University between 1971 and 2000. The surveys addressed diverse natural resource-based topics and involved a variety of study populations. We tested the null hypothesis that response rates to natural resource-focused mail surveys are not changing over time. We found the best multiple regression model (adjusted R-2 = .558) to explain differences in response rates incorporated five independent variables: (1) saliency of study topic to surveyed population, (2) the month of the first mailing, (3) the size (font) of print type, (4) the number of complex questions included in the survey, and (5) year of survey implementation. All other variables held constant, the model suggests that response rates dropped on average 0.77% per year over the 30-year period. The scatterplot of response rate versus time suggests a gradual decline in response rates over time.