I’ve just finished reading this book and I would strongly recommend it to anybody seeking to understand the methods and challenges of measuring phenomena in social media. The book is probably stronger on talking about things that don’t work, as opposed to things that do work, but in this time of hype that is probably no bad thing. For example, the book shows why the ROI of many types of activities can’t be measured without making some large assumptions about how things work, and point out that in many cases it is the ‘R’ in ROI that is the problem.
Key themes addressed by the book include metrics for different sorts of social media activities, the problems of assessing causality, the tension between influencer models and homophily, and the difference between reach and intent. The book provides an excellent list of links to further sources (especially if reading the ebook), and provides a great overview of measurement in areas such as social media marketing, CRM, sales, and PR.
This is the best primer on the subject I have read so far and it is, at the moment, sparklingly up to date.
The print copy of the book is not currently available in the UK (and probably lots of other places too as it was only published in the US in January 2014) but it is available on Kindle, and if you buy it directly from O’Reilly Media there is some sort of update/extension deal available.