  ### Appendix B (Estimating the Number of Interviewers Needed for a Study)

This example shows how to calculate the number of interviewers required for a hypothetical study. The example makes the following assumptions:

1.       Interviewers and respondents do not need to be matched on any attributes.

2.       The average number of hours worked per week is the same for all interviewers.

3.       The expected number of completed interviews is 500.

4.       The estimated hours per interview (HPI) is 5.

5.       The projected data collection period is 5 weeks.

6.       Each interviewer is expected to work 15 hours per week (based on the optimal hours of work during the times the respondents are expected to be at home).

Make the following calculations:

1.       Total hours to complete the study = (500 interviews * 5 HPI) = 2500 hours.

2.       Average interviewer hours per week = (2500 total hours / 5 weeks) = 500 hours per week.

3.       Number of interviewers needed = (500 hours per week / 15 hours per interviewer per week) = 33 interviewers.

To determine the optimum number of interviewers based on interviewer variance and cost, see .

Reference