Nielsen’s Undercounting Fiasco Linked to Social Gaming

When Nielsen confirmed yesterday that its NetView service had seriously underreported online time-spent data, it pointed the finger at a glitch in its system that intermittently blinded the measurement firm to user sessions on Web pages with very long URLs. But it wasn’t immediately clear what had caused the problem, or why it had gotten worse over time.

Nielsen now believes the issue is related in part to social gaming, which can result in such protracted URLs – especially when embedded on another page.

The counting problem – first reported by AdAge on Thursday – was initially observed by Nielsen over the summer. “We started seeing a decline…and our clients noticed it as well,” said Ari Paparo, Nielsen’s EVP of online products. “When the decline became more extreme over the next several months, it was all hands on deck.”

An investigation revealed that erroneous data occurred when Nielsen’s system failed to process session data with URLs that were more than 2,000 bytes in size. The flaw led to an average 22 percent decline in time spent year-over-year, Nielsen estimates.

The measurement company has initiated a fix that will take effect with its December data; that data will be reported in January. Until then, Nielsen is urging clients to limit their use of the NetView product, along with other products that it believes are affected to a lesser extent. These include VideoCensus, MegaView Retail, MegaView Search, AdRelevance, and WebRF.

Nielsen continues to look into the issue, and Paparo says it would be inaccurate to blame it entirely on social networks and social gaming destination sites. But he said, “It definitely looks like technology related to social networking and gaming.”

Additionally, Nielsen says that metrics other than time spent have likely been affected by the URL problem. Page view calculations are probably off, said a spokesman, while the company is still making a determination about the impact on unique audience data.

Nielsen was contrite in a letter to clients. “This investigation, covering every element of our Internet measurement methodology, including the panel, collection capabilities, and processes, and nature of the root cause indicates that we need to do a better job keeping pace with the rapid evolution of the Internet,” it said. “We are putting new processes in place to add greater rigor to the continuous testing of our methodology and expanding our monitoring for anomalous events.”

The next step for Nielsen is to carry out a similar investigation in overseas markets. It will also work with the Media Rating Council (MRC) to review its findings and new processes.

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