Citation for the article:
Luo, Lili. "Chat Reference Evaluation: A Framework of Perspectives and Measures." Reference Services Review 36.1 (2008): 71-85.
Read via Emerald.
I just wanted to make a note of this article, but I don't have anything substantial enough for the main blog. It provides a review of procedures for evaluating chat reference services. It basically goes through the literature, and it summarizes the various approaches available for evaluating chat reference. Overall, a decent overview.