Research using blogs for data: public documents or private musings?

Nursing and other health sciences researchers increasingly find blogs to be valuable sources of information for investigating illness and other human health experiences. When researchers use blogs as their exclusive data source, they must discern the public/private aspects inherent in the nature of blogs in order to plan for appropriate protection of the bloggers' identities. Approaches to the protection of human subjects are poorly addressed when the human subject is a blogger and the blog is used as an exclusive source of data.