Skip To Main Content

ESG Data: Biases and Limitations

What We’ve Been Reading & Listening To
April 25, 2018

Months ago, I saved an issue of Journal of Environmental Investing fully intending to read it—and after carrying it with me for more than 50,000 air miles, I eventually did. I’m glad I held on to it. With the proliferation of ESG (environmental, social, and governance) data, ratings, and indexes, it is helpful to see these metrics considered comprehensively and with some perspective, divorced from the marketing packaging that seems to drive much of the related discussion. In particular, the first section on The Ecosystem of ESG Data, with contributions by Dan Etsy and Todd Cort of Yale University, is particularly useful. This is not to suggest that we agree with all points made or even that within Aperio we all have a uniform view but rather that we found it to be a thoughtful presentation of the issues and a great starting point for further research and discussion.

No data set or rating is ever perfect nor removed from the subjectivity of the creator, but in order to make the most informed decisions about its use, it is important to understand what biases and limitations are built in. For each investor and user, what is acceptable and what isn’t will likely vary.

Send questions or comments to

This article is provided for informational purposes only. The information contained within this article was carefully compiled from sources Aperio believes to be reliable, and it is accurate to the best of our knowledge and belief. However, Aperio cannot guarantee its accuracy, completeness, and validity, and cannot be held liable for any errors or omissions. All information contained herein should be independently verified and confirmed. Aperio does not accept any liability for any loss or damage whatsoever caused in reliance upon such information. Aperio provides this information with the understanding that it is not engaged in rendering legal, accounting, or tax services. In particular, none of the examples should be considered advice tailored to the needs of any specific investor. Aperio recommends that all investors seek out the services of competent professionals in any of the aforementioned areas. With respect to the description of any investment strategies, simulations, or investment recommendations, Aperio cannot provide any assurances that they will perform as expected and as described in this article. Past performance is not indicative of future results. Every investment program has the potential for loss as well as gain. You cannot invest directly in an index.