Effects of form length and item format on response patterns and estimates of physician office and hospital outpatient department visits. National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey, 2001.

Objectives: This report describes effects due to form length and/or item formats on respondent cooperation and survey estimates.

Methods: Two formats were used for the Patient Record form for the 2001 NAMCS and OPD component of the NHAMCS: a short form with 70 subitems and a long form with 140 subitems. The short form also contained many write-in items and fit on a one-sided page. The long form contained more check boxes and other unique items and required a two-sided page. The NAMCS sample of physicians and NHAMCS sample of hospitals were randomly divided into two half samples and randomly assigned to either the short or long form. Unit and item nonresponse rates, as well as survey estimates from the two forms, were compared using SUDAAN software, which takes into account the complex sample design of the surveys.

Results: Physician unit response was lower for the long form overall and in certain geographic regions. Overall OPD unit response was not affected by form length, although there were some differences in favor of the long form for some types of hospitals. Despite having twice the number of check boxes on the long form as the short form, there was no difference in the percentage of visits with any diagnostic or screening services ordered or provided. However, visit estimates were usually higher for services collected with long form check-boxes than with (recoded) short form write-in entries. Finally, the study confirmed the feasibility of collecting certain items found only on the long form.

Conclusion: Overall, physician cooperation was more sensitive to form length than was OPD cooperation. The quality of the data was not affected by form length. Visit estimates were influenced by both content and item format.