2.3. Instrument, validity and reliability

The instrument used in the research was a researcher-made questionnaire. The questionnaire consisted of two parts. The first part comprised demographic data with 16 questions on age, education, occupation, and duration of diabetes, while the second part included 17 questions on knowledge. Each question was scored 3 for the right answer, 2 for ‘I do not know’, and 1 for the wrong answer. The range of knowledge score was from 17 to 51. The validity of the questionnaires was measured using qualitative content and face validities. The questionnaire was given to 30 diabetic men to confirm the face validity. Their oral comments were obtained and administered to correct the questionnaire. Cronbach’s alpha was calculated as 0.82 and confirmed as a desirable reliability.