Nielsen informed clients this week that it may have under counted website traffic data at a number of US websites. The affected Nielsen product is NetView, but there are likely issues with the VideoCensus, MegaView Retail, MegaView Search, AdRelevance, and WebRF services, as well, the data intelligence company said in a letter to clients obtained by AdAge.
“We are writing to inform you that we are actively investigating an erroneous decline in our Internet use data,” it wrote.
Long URLs, which frequently result on social media, appear to be the culprit that caused an “estimated average 22% decline in time spent year-?over-?year,” according to the letter.
Nielsen said it will correct reporting data for the month of December, which will be released in January 2011.
Page impressions, unique visitors and time spent on site and individual pages are all important metrics to a number of industries. Certainly here at Direct Marketing News, we rely on an independent auditor, BPA Worldwide, to confirm our traffic to readers and clients. Having a key metric off by 22% can’t have made anyone happy and Nielsen is smartly saying it will review its methodology and continue testing in order to right this data slip up.