ROI for Corporate Blogging?

Charlene Li questioned the math for calculating the ROI of Blogs. She wrote:

I tried to address this question recently in a speech at the New Communications Forum where I said my blog could be associated with $1 million of revenue at Forrester. I shouldn’t have tried to attach a number to my blog’s ROI because in the end, it’s a highly subjective, qualitative measure that’s hard to measure.

The word "associated" is spot on. Charlene's blogging has some impact, positive or negative, on the revenue derived from her practice (and potentially others' practices). My vote is that there is a good answer to this question, or at least a range and an approach. The equation may look like the following:

Charlene's blogging value =

(Net increased (decreased) revenue from Charlene's practice +

Net increased (decreased) retained revenue (over normal baseline) from Charlene's practice)

* Share of blogging compared to other PR, Marketing and Sales activities.

If her practice earns $1M in new revenue this year and retained $100K that would normally be lost, then a measurable portion (within a range, lets say 5% to 30%) of the $1.1M is attributed to the blog.

I blog internally as part of my work process, it's like drinking water. It's just how we communicate and build information resources.

I blog externally to participate in what seems like a global collaborative experiment. E.g. this post is part of a collaborative process with Charlene and at least 7 others who left comments and to increase my involvement in the global KM community.

As a result of writing KM is the Forest, Enterprise Blogs are the Path, KM World contacted me about adapting the blog post into a presentation on Enterprise Blogs and Wikis at their annual conference this October... I can measure that. Return achieved.