I've been blogging for 10 years, and I've written over 800,000 words in posts. As time progresses, I try to clearly convey more information with fewer words. It's been hard to quantify the value derived from those words, however, since the only measurements I could make (e.g. a small amount of ad revenue) have been subjective at best.
For almost seven months, I've been writing Ansible for DevOps, publishing on LeanPub as I write. In that time, I've written ~41,600 words (with roughly 60% of the book complete), and have had ~800 readers purchase the book (either standalone, or in a bundle).
Writing this book has, for the first time, allowed me to put a dollar value on my words—and helped motivate me to try to write and edit more effectively. Through many iterations (14 published releases), I've been tracking the amount of money I've made per word, and though I don't yet have the full data set to play with (I have other priorities, like a new baby and a new full-time job, so expect more data in a future post!), each word I type is worth about $0.21 (slightly more, if you count the net sales of the book).
While I'm still heavily into the writing of this book, and haven't yet reached a final first draft, I've been editing heavily (both on my own and with help), cutting down the word count and removing cruft. My goal is to push the price per word past $0.25, and I hope I can achieve this even before listing the book on the Kindle marketplace or other self-publishing channels.
There would be no simple way to determine this without LeanPub, which is a great publishing platform (most especially for those who choose to publish-as-they-write), so I'm grateful that LeanPub has enabled me to write this book, discover what it takes to actually write a full-length (40k+ words) technical book (hint: a lot more than I thought... and I'm not yet finished!), and earn money while writing so motivation is built into the process.
It would be difficult to support a family with the amount of money made writing a book like Ansible for DevOps—or even multiple technical books—but if you have deep knowledge of a particular product, area, or technique, and enjoy writing, it's worth at least writing and editing a few chapters, putting your work on LeanPub, and seeing what happens!