How do you judge the value of expertise on the Web? Does it differ from your notion of expertise in face-to-face settings? Why or why not?
In face-to-face setting, I would think that officially expertise would require both qualification he/she receives and deep professional experience before they can be viewed as experts. The qualification comes through professional training or academic certification and years on specific experience on the subject. For example, in civil engineering, you need to have a degree and 10 years of consulting with site experience before you can apply to be a professional engineer to certify structural designs. On the other hand, there are people who may not have the academic qualification but have years of deep experience on the subject (e.g. car mechanics), this I would term as unofficial type of experts.
In web setting, experts are probably people who provide high quality contributions to the online community through their blogs, comments, posts and articles. However it is difficult to determine the qualification or experiences in the web setting thus their contributions represents their value and expertise. A measure of their value can be quantified by the amount of followers or likes on their articles. Some web blogs that generate high rate traffic sometimes get the attention of companies who will offer pay the blogger to write about the company as a form of marketing strategy (e.g. food industry). There are web base communities that rank their members the amount of contributions they have made however I would argue that not all contributions value adds to the community. Hence it would be important that all web users to exercise discretion on the information provided. I think in a web setting everyone can be in someway an expert as long as your contribution is positively recognized by the masses.