Parameters:
(1) number who completed the questionnaire and who qualify = group 1
(2) number who responded but who did not qualify = group 2
(3) number who refused to participate = group 3
(4) number who could not be reached = group 4
total subject population =
= SUM(number in each of the 4 groups)
response rate =
= (group 1) / (X)
X =
= (group 1) + ((group 1) / ((group 1) + (group 2)) * ((group 3) + (group 4)))
where:
• Of those who responded, a certain number do not qualify.
• The assumption is that the same percentage of people in those who did not respond would not have qualified.
• The denominator then becomes the total number of people in the population who would qualify and respond if there had been a 100% response rate.
