BPA Worldwide: 95% of websites may be undercounting traffic

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Online audience measurement, especially for b-to-b media sites, is never as simple as promised. Earlier this week, BPA Worldwide said 95% of websites may be undercounting traffic due to underuse of JavaScript tags.

Consider the wide variations in traffic measurement figures for two Informa Business Information niche websites: BioTechniques ( BioProcess International (

In a recent study, BPA tabulated that had 64,969 unique visitors in August. Audience measurement site had a significantly smaller figure: 11,810.

Similarly, had 3,800 unique visitors in August, according to BPA. had no figures for, which implies that the statistical sample was not large enough.

Some of the discrepancy can be attributed to the different methodologies used by BPA and BPA uses a census-based system, where it determines unique visitors by consulting a site's servers. The downside of this approach is that it's difficult to gauge the demographics of visitors. (Additionally, this approach must filter spiders and bots and also account for cookie deletion, which can inflate unique visitor counts).

On the other hand, and other online audience measurement companies, such as comScore, use panel-based measurement. By their nature, these panels are composed mainly of consumers and chronically undercount b-to-b traffic, observers say. However, these panels do provide more complete demographic characteristics of audiences.

Surprisingly, even though BPA's census-based figures for b-to-b websites tend to be markedly higher than panel-based measurements, BPA said that many of the websites it audits are likely undercounting their audiences. As a result, these websites may be leaving money on the table.

BPA, which uses ObservePoint technology, estimated that 95% of the sites it analyzed had not placed JavaScript tags on many Web pages. It said an average of 20% of all Web pages it analyzed went without a tag. The tags allow BPA to count unique visitors and impressions.

“If websites contain pages that are untagged, the potential is there for media owners to considerably underreport the amount of traffic to their sites,” Peter Black, BPA's senior VP-business development, said in a statement. “ObservePoint technology allows us to uncover those pages that are not tagged and ensure sites are getting full credit in the eyes of online advertisers and media buyers.”

On its BioProcess International site, Informa Business Information may have been undercounting its audience by overlooking JavaScript tags. “It was incredibly comforting to know that BPA has been checking our site regularly to ensure the tag was functioning properly,” said Rindy Portfolio, technical development manager at Informa. “When we switched websites and forgot to move the tags, BPA alerted us that they weren't receiving any data, and we were able to quickly resolve the situation.”

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