Secondary data (SD) provides major advantage in the use of existing data sources, with large amounts of information, at relatively cheaper cost and easily available for research purposes. Even some researchers argue that millions of person-years of experience in the database will be available through SD, which would be impossible to collect in prospective studies. But an unreliable data could impede on the quality of research results and conclusions. The study critical examination of literature has identified tools that can aid the assessment of SD reliability. The study believes that the use of the adjusted inter-raters/observer as proposed by the study will add value to the method of assessing the reliability of SD, because of it use of statistical tools to directly estimate the available data. The study also believes that this will serve as a base for other researchers to improve on the study of assessing the reliability of secondary data.