The Effectiveness of Advance Letters for Cell Telephone Samples
Benjamin Skalland
NORC at the University of Chicago
Zhen Zhao
National Center for Immunization and Respiratory Diseases
Jenny Jeyarajah
National Center for Immunization and Respiratory Diseases
Traditionally, address matching was possible only for landline RDD telephone samples. It is now possible to obtain addresses for a sizeable proportion of RDD cell telephone numbers, and the use of advance letters for these numbers may result in an increase in response rates similar to those seen for landline telephone numbers. To test this, addresses were obtained for samples of landline and cell telephone numbers in the 2013 National Immunization Survey, a large, national, dual-frame RDD survey sponsored by the CDC and fielded by NORC. Advance letters were mailed to half of the cases in the landline and cell telephone samples with addresses. We found that while advance letters had a positive effect on screener completion in the landline sample, they did not impact screener completion in the cell telephone sample. The lack of effect in the cell telephone sample may be due to a high rate of inaccurate address matching: recently-updated addresses were found to be more accurate, and when the analysis was restricted to advance letters mailed to recently-updated addresses, the impact on screener completion in the cell telephone sample was similar to that in the landline sample.