Development and Psychometric Testing of an Instrument to Measure Determinants of Mammography

Mammography is the most effective way for early detection of malignant breast masses. This study aimed to develop and evaluate the psychometric properties of a context-based measurement tool for assessing determinants of doing mammography through inductive approach.
The present study was a sequential exploratory study. In the first phase the determinants of doing mammography were explored using the content analysis approach. The data were collected via 21 semi-structured interviews by 15 participants in Urmia, Iran. In the second phase the statements were formed based on the meaning units, which extracted from qualitative section. The validity of the instruments was assessed using face, content and constructs validity assessment methods. For evaluation of face validity, qualitative and quantitative (item impact score) methods were used. The content validity was assessed by 10 experts. The construct validity was calculated by exploratory factor analysis. The sample size was calculated by multiplying the number of items by five. Internal consistency, and intraclass correlation coefficient (ICC) were used to assess the reliability of the instruments.
An instrument had 7 components and 34 statements. The components of the instrument included: beliefs, access, knowledge, action cues, emotions, self-care and life priorities. Seven components explained 57.28% of variance. The instrument was found to have high internal consistency (Cronbach's α = 0.78) and adequate test-retest reliability (ICC = 0.91).
The present instrument is a comprehensive measure related to determinants of doing mammography. It could help to determine factors influencing mammography and conduct interventions to improve women’s behavior for doing g mammography.