Time and cost analysis of a computer-assisted telephone interview system to collect dietary recalls

This study, conducted in 1991, examined the time requirements and costs of obtaining 24-hour dietary recalls via telephone interviews using the University of Minnesota's microcomputer Nutrient Data System to conduct the interviews and compute the nutrient composition of the diets. The subjects were 156 hypercholesterolemic children (aged 4-10 years) and 102 hypercholesterolemic adults (aged 21-65 years), who were participating in ongoing cholesterol education programs. A total of 391 recalls were completed with the children and 278 with the adults. For each completed interview, 3.5 and 2.8 attempts were required, respectively. Evenings were the most productive time for completing interviews. All tasks associated with completing the interviews (attempts to call, interviews per se, and postinterview procedures) required an average of 39.7 and 35.5 minutes per completed interview with the children and adults, respectively. About half of these total times were actually devoted to conducting the interview. The costs per completed interview were $9.22 for the children versus $6.99 for the adults. This difference reflects the greater number of attempts required to reach the children, the longer duration of their interviews, and the higher intrastate toll rates for calls to them as compared with the interstate rates for calls to the adults.