Tesfaye, Fikru(PhD)Berhane, Yemane(Professor)Tadesse, Zerihun2018-07-272023-11-052018-07-272023-11-052004-04http://etd.aau.edu.et/handle/123456789/10290According to a substantial body of evidence, regular physical activity can bring significant health benefits to people of all ages and abilities. Scientific evidence increasingly indicates that physical activity can extend years of active independent living, reduce disability and improve the quality of life of young and older adults. Despite these evidences, little is known about physical activity or its measurement on a population basis. A cross-sectional community based study was conducted to assess reliability and validity of instruments for measuring levels of physical activity. The instrument with better reliability and validity was used to measure levels and assess determinants of physical activity. Simple random sampling was carried out to recruit a total of 940 subjects. Global Physical Activity Questionnaire (GPAQ) and International Physical Activity Questionnaire (IPAQ) were administered to all participants during the first contact. The questionnaires were administered again after 4 days to a randomly selected sub-sample of 151 participants in order to assess reliability. Validity of the questionnaires was assessed on another randomly selected group of 186 study participants who wore motion monitor for seven consecutive days. A set of reliability tests indicated that GPAQ and IPAQ had good repeatability; balance in favor of the former. Validity of the questionnaires was assessed by a number of methods. Unlike reliability, validity was modest: percent correctly classified by concurrent validity of GPAQ against IPAQ for various domains of activity was between 35.9 and 42.5; gross vii misclassification was in the range 17.7-26.3%. In criterion validity test of the questionnaires against motion monitor, percent correctly classified was between 21.0 and 35.5 for GPAQ and between 25.3 and 38.2 for IPAQ; gross misclassification was in the range of 21.1-40.3% for GPAQ and 18.3-41.9 for IPAQ. The prevalence of physical activity measured by GPAQ was found to be 77%(724/940). Cumulative assessment of reliability and validity of questionnaires used in this study indicated that GPAQ and IPAQ were appropriate for use in our setting. However, conducting similar reliability and validity studies across different seasons and regions is strongly recommended before applying them on large-scale studiesenInstruments for measuring levels of physical activityThesis