VITAMEDIAS
Ratings Agency Says It Erred in Measuring Web Site Use: Web ratings services have faced questions about accuracy since they began trying to estimate audiences by projecting the behavior of a panel of presumably representative users. Despite their limits, ComScore's ratings, and those of its main competitor, Nielsen/NetRatings, are widely used by advertisers, investors, journalists and the Web sites themselves.
The biggest differences in ComScore's ratings, announced last week, come in its estimates of Web use at the workplace, always the most difficult to measure. Big companies in particular do not want employees to install the software that the ratings companies use to track Web site usage. When ComScore adjusted its formulas to account for the underrepresentation at big companies, its audience projections increased, in some cases sharply.