Traffic
Unique pageview
Also called unique page view.
Unique pageview is the number of sessions in which a given page appeared at least once. It collapses repeat views inside a sitting into one.
How it is measured
For each URL, count the sessions that contain at least one pageview of it. Refreshes, back-button returns and a second visit to the same page in one sitting add nothing.
In Tarsier a session lives in one tab, so reading the same page in two tabs counts it twice. Reload inside a tab counts once.
Worked example
A tax-calculator page shows 5,000 pageviews and 3,100 unique pageviews in a month. People recalculate about 1.6 times per sitting, so the unique figure is a closer match to how many sittings used the tool.
Later the developer adds a recalculate button that reloads the page. Pageviews jump to 7,400, unique pageviews barely move, and the team sees at once that the jump is the button, not demand.
How it differs
A unique pageview counts a page once per session. A pageview counts every load. A unique visitor counts people across a period. The first two are tied to sessions, the third to identifiers, so you cannot move between them by arithmetic.
Common errors
Calling it unique people. Summing unique pageviews across pages and calling the total sessions. Comparing counts built with different session timeouts. Forgetting that redirects can create extra loads. Using it for site totals.
In practice
Use it for pages where repeat loads are noise: calculators, dashboards and search results. For site-wide traffic stay with sessions.