About This Book

The contents of this book show the analysis associated with an eLetter to science in response to West et al. (2023)¹. The main work presented in this web book are interactive maps for each of the projects considered in the paper¹ . We focus here on the project-level analysis, undertaken as part of that publication, where the authors constructed synthetic controls (SC) from randomly distributed circular donors from across the country of each project. In the supplementary materials for the paper, only the code to reproduce results for the Colombian Project 856 were provided.

We have attempted to reproduce the results across all considered projects to evaluate whether potential issues, identified for project-856, exist more generally for other project synthetic controls. Further, it is an opportunity for us, as researchers, to gain a greater understanding of how the proposed method works.

In order to reproduce the results for the remaining sites, we are missing “problematic donors” excluded from the SC matching step and the filtering threshold for buffer area deforestation rates. We have automated the filtering threshold such that when too few donors are selected or an error results from the SC matching, the process is rerun with the threshold increased by 10%.

Therefore, the maps presented here do not precisely match those presented by the authors in the Supplementary Materials (Fig. S4.). However, this exercise is still informative regarding the general applicability of the methods and to what extent they improve on existing manual/selective evidenced-based methods that are currently adopted.

1.

West, T. A. P., Wunder, S., Sills, E. O., Börner, J., Rifai, S. W., Neidermeier, A. N., Frey, G. P. & Kontoleon, A. Action needed to make carbon offsets from forest conservation work for climate change mitigation. Science 381, 873–877 (2023).