Four cluster trials datasets were used in this study as case studies. They are:  PoNDER trial, Bridging the Age Gap trial , Informed Choice trial and Nourishing Start for Health (NOSH) trial.   These four case studies of cluster randomised controlled trials had number of clusters ranging from 10 to 100 and individual participants ranging from 748 to 9,207. All the datasets are secondary data and completely annonymised, and cannot be traced to the participants in the original studies. Hence, no ethical approval was obtained. ICTMC 2022