What are the differences between the MSA, PDF or STAR metrics? The ABMB project provided in-depth comparisons of the 3 metrics and others and is an under-used treasure for all those interested in biodiversity impact measurement.   📄 This table from the Aligning Biodiversity Measures for Business (ABMB) project compares the aggregation method behind 6 key metrics (and list the tools using those metrics): - #MeanSpeciesAbundance (MSA) - Potentially Disappeared Fraction (PDF) - Species Threat Abatement and Restoration (STAR) units - Biodiversity impact index - Monetary values - Qualitative/score card 💡 It details the reasoning - which partly reflects the (sometimes ethical) values behind the metric – justifying each aggregation method and lists the limitations associated with each.   🌲 For instance the MSA is focused on ecosystem condition and not on the risk of extinction of species. As a result, optimising for MSA means we could still lose endangered species such as the Siberian tiger. That calls for the use of a bundle of complementary metrics covering each other’s limitations. In my opinion, that should be 1 metric for ecosystem condition, 1 metric for the significance of biodiversity covering extinction risk (species), protected areas, Key Biodiversity Areas, ideally 1 metric for genes (but I haven’t identified any), and then additional indicators for ecosystem services.   Please note that for MSA, it is possible (though very costly and difficult) to directly measure biodiversity state so the first limitation listed applies only when characterisation factors (e.g. MSA.m2/t of commodity) are used.   ❓ Unfortunately, at the time of drafting of this report, some metrics such as the Ecosystem Integrity Index (EII) did not exist yet so they are not part of the table. If you see other metrics used by corporates and financial institutions missing, please let me know in comments, to feed future updates of this work.