A zip file containing an .R script with R code to run simulations and a .csv file containing data to load into R to run simulation. This data was extracted from 47 ecological studies and characterises the change in control and impact sites, as well as differences between these sites before an impact occurred, as per detailed methodology in the paper Christie et al. (2019). Data is also present in another .csv file showing results of when the accuracy weights presented in the paper Christie et al. (2019) were used to rerun the results of several meta analyses. We compare the results obtained from these accuracy weights with those obtained by using inverse variance. There is also a .txt file containing a link to a shiny app that will allow the calculation of accuracy weights based on Christie et al. (2019).