THE VALIDITY AND RELIABILITY OF AN ASTHMA KNOWLEDGE QUESTIONNAIRE USED IN THE EVALUATION OF A GROUP ASTHMA EDUCATION SELF-MANAGEMENT PROGRAM FOR ADULTS WITH ASTHMA

This paper reports aspects of the validity and reliability of an asthm a general knowledge questionnaire for adults (AGKQA), developed as one of the outcome measures for a randomized controlled effectiveness tri al of an asthma education program for adults with asthma. It also illu strates how study data can provide a valuable, generally neglected opp ortunity to assess the validity and reliability of a measure where res ources are not available for the extensive investigation of these prop erties prior to administration of the measure in a study. The AGKQA wa s demonstrated to have good content and face validity. Construct valid ity assessed using the principal components method for factor analysis suggested the scale was unidimensional. Criterion-related validity, a ssessed using the contrasted groups method, demonstrated a significant difference (p < 0.0001) in total score and for 68% of item responses for the adults with and without direct experience of asthma. The Kuder -Richardson 20 reliability coefficient for internal consistency calcul ated using responses at baseline, immediately, and 12 months post-inte rvention were, respectively, 0.56, 0.80, and 0.75, indicating excellen t reliability. The AGKQA is an acceptably valid and reliable measure f or the assessment of program content mastery that it was designed to t est.