Steps for Calculating and Reporting on Reach

The following is a recommended sequence of standard steps for calculating and reporting on Reach:

  1. Enumerate all potential participants in the target population (usually defined geographically).
  2. List the reasons for and number of exclusions by the investigators or program.
  3. List the number of “lost or indeterminate cases” – e.g., wrong information, not able to be contacted, moved, no answer.
  4. List the number of known eligible participants who were offered participation.
  5. Divide the number of participants (persons beginning or coming to the first session of a program) by #4 to determine Percent Participation.
  6. (Optional) A sensitivity analysis can be conservatively calculated by adding #3 and 4 in the denominator and then dividing, as in #5.
  7. Determine the representativeness of participants by comparing demographic characteristics and other relevant variables between participants and nonparticipants.
  8. Report the most common reasons for declining participation.