The fact that the items were evaluated iteratively for face validity with regard to comprehensiveness, relevance and comprehension in a panel of experts in paternity research and in a pilot study of first time fathers also supports the validity of the questionnaire.
For further evaluation of item clarity, relevance, and comprehension, subjects were drawn from the Stanford PROMIS Primary Research Site study cohort.
Cognitive interviews are then conducted to verify the relevance and comprehension of the instrument to the population of interest.
We evaluated retained items for content, clarity, relevance and comprehension, reading level, and translation ease by experts and patient surveys, focus groups, and cognitive interviews.
The questionnaire was pilot tested on 50 health workers from a hospital not involved in the study to check relevance and comprehension and amendments made to promote clarity as required in line with good practice [ 21].
Cognitive interviews were carried out in patients (n = 20) to refine and test the content validity of the instrument in terms of item relevance and comprehension, instructions, recall period, and response categories.
After pre-testing for relevance and comprehension a pool of 181 ADL items were answered on a five-point Likert scale by 720 CVD patients, who were recruited in fourteen German cardiac rehabilitation centers.
The survey, at all stages coded for anonymity, was first pre-tested for relevance and comprehension by school students of the corresponding age groups, and thereafter in a pilot study in November 2000 with 103 students from grade 3, 6 and 9.
The comprehensibility, comprehension and relevance of the items were evaluated by four paternity research experts and a preliminary questionnaire was pilot tested in eight first-time fathers.
