Meta-analysis is the preferred technique of quantitative research synthesis in many fields, such as
medical science. It is a statistical technique that combines measures of
effect size from a number of studies to calculate an overall measure. This measure of effect has greater
precision (less uncertainty) than the individual studies, but it may be biased by differences between the studies in study design, the type of evidence, or other key characteristics. The narrative synthesis approach has attracted criticism because of its potential for bias, with critics highlighting the subjective nature of the use of the method to draw conclusions. There is also evidence that reviews using the narrative synthesis approach often suffer from a lack of transparency. == References ==