Nielsen/NetRatings is changing the way it measures audience engagement on Web sites. It is replacing visitors’ page views with total time spent on a site.

“‘Total Minutes’ is the best engagement metric in this initial stage of Web 2.0 development, not only because it ensures fair measurement of Web sites using RIA [rich Internet applications such as AJAX] and streaming media [audio, video, data tickers, etc.], but also of Web environments that have never been well-served by the page view, such as online gaming and Internet applications,” said Scott Ross, director, productmarketing for the NetView service. (See Nielsen’s press release.)

On the other hand…

Blogger Scott Karp (Publishing 2.0) offers a cogent summary of why “total minutes” may be an imperfect metric.