Commencing its ninth year online, Economic Principals is making a couple of significant changes in its operation. The Web has changed enormously since EP moved online in early 2002.

The blogosphere, which scarcely existed ten years ago, has become a vibrant new medium, competing for attention with books, newspapers, magazines, film, radio, and television.

William Parke, of the University of North Carolina at Chapel Hill, tracks 147 economics blogs in an RSS feed at Economics Roundtable with some annotation, not much, in the right rail of his page; while at Economist’s View, Mark Thoma, of the University of Oregon at Eugene, lists 371 blogs from around the world (his blogroll), edits the best of them with varying degrees of intensity, and provides his own commentary at intervals throughout the day. He hasn’t failed to post some material of his own on a single day since he began, in 2005.

From the outset EP has insisted that it is not a blog. It remains weekly journalism – a column not much different from the evolving feature of a Sunday newspaper (The Boston Globe) that it was for 18 years, despite the fact that it is now distributed online. Technology, however, has made it possible to incorporate two new features.

Starting next week, I am opening the weekly to comments. They will be moderated and, in all likelihood, sparse. The idea is not to encourage readers to chat back and forth in real time, an endearing feature of many blogs, but to provide a letters page, an opportunity to share disagreements or elaborations written mainly for the benefit of other readers.

This week I’ve added a j-roll – a series of links to around 60 economic journalists whom I read, whose opinions matter most to me, with whom I try to keep up. (Go to the Webpage and have a look. Next week the links will collapse beneath a button in order to preserve the simplicity of the page.) There was a time when it could be said with confidence that there existed an invisible college of reporters who read each other’s stuff, shaped each others’ reputations, and coveted each others’ jobs. With the vastly expanded world of the blogosphere, and the correspondingly diminished world of print journalism, who can be sure any longer how reputations are made and sustained?

What is clear is that link exchanges, in the form of blogrolls and the daily wash of commentary on one another’s sites, are the motive force of the blogosphere. This is the mechanism known as collaborative filtering. It is the essence of the system of scientific citation as well. Its power is no harder to fathom than the logic of publishing best-seller, top-forty and most-read lists. Collaborative filtering doesn’t operate in a vacuum, of course; it goes hand in hand with evaluation, prizes and criticism wherever it is employed.

But on the Web, in combination with the proprietary algorithms with which search engines measure Web traffic and send searchers to the most popular sites, reciprocal links determine who gets read. Such ritual mentioning is not as efficient with print journalism, but it works there, too. Circulation is not everything, but it counts for much.

In the end, what’s the difference between bloggers and journalists? It is not frequency. Many journalists blog now, and many bloggers do journalism, illuminating dark corners which they may know better than anyone else.

The real difference has to do with. the nature of the writer’s day job. Most bloggers make their living working for somebody else – a company, a political party, a think tank, a military unit, a religious community, a university, a profession. Their ultimate loyalties are likely to be to their day job, and their career. There may be many sacred cows for them, or relatively few, but there certainly will be some, and it won’t matter to them very much.

Journalists, on the other hand, are paid for their work. Gathering and presenting information is their day job. They work for the reader (though, to the extent they depend on advertising, they may shade their coverage one way or the other). They like to think they know their way around a sacred cow; when to ginger, when to milk. It is a good idea to keep these distinctions in mind.

For above all, the production and consumption of news is a matter of time. The blogosphere had increased the general scarcity of time, almost painfully for a certain kind of citizen. How to spend what time we have?

The stream of consciousness that is the essence of a good blog? All intimacy, impact and insistence? Or the reporting, editing and disinterestedness that together constitute good journalism? My hunch is that the editorial frame is something for which substantial numbers of citizens will remain willing to pay, on paper, in broadcast and online.