About the review's Research Questions
The area of the systematic review and the specific research questions set the focus for the identification of the primary studies, the extraction of data from the studies and the analysis. Hence, the research questions must be well thought through and phrased. Aspects to take into account in phrasing the research questions include the PICOC.
C. Wohlin, P. Runeson, M. Höst, M. C. Ohlsson, B. Regnell and A. Wesslén, "Experimentation in Software Engineering", Springer, ISBN 978-3-642-29043-5, 2012.