Appraising the state of measurement of Islamic religiousness

Given that measurement is a vital element of scientific research of religious phenomena, we examine how well-developed the Islamic measurement literature is by systematically reviewing, summarizing, and evaluating the available measures of Islamic religiousness that are grounded in Islam. Our evaluation is based on 5 criteria: theoretical clarity, sample representation, reliability, validity, and generalizability. Most measures are theoretically sound and have produced reliable scores, but concerns are raised regarding the external and predictive validity of many of the instruments' scores. Our evaluation also points to the need of (a) refinement and further validation of some instruments, (b) exploring the distinction and overlap of the constructs religion and spirituality from an Islamic perspective, and (c) testing the applicability of some further constructs (e.g., attachment to God, religious and spiritual development) to the Muslim context.