> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vertracloud.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Web Analytics Sampling and Delay: How Accurate Are the Numbers?

> With high traffic Web Analytics estimates figures and samples requests, and data arrives a few minutes late. Here is what that means for you.

Web Analytics numbers are accurate for normal traffic, estimated for very high traffic, and a few minutes behind real time. A notice in the panel tells you when either applies.

## Sampling

Measuring every single request of a very busy app is not practical. When traffic is high, the edge keeps a statistically representative sample and scales the figures up:

* **Totals and percentiles** are estimates. They are reliable for trends and comparisons, and they can differ by a small margin from an exact count.
* **The Requests table** shows a sample of the requests, not all of them. A specific request may not be in it.
* A **sampled** notice appears in the panel whenever this is happening. Apps with low or moderate traffic usually see exact data.

A narrower period or a filter does not turn an estimate into an exact count, but a very short window on a busy app can look uneven because few samples fall in it.

## Delay

Data refreshes about every 5 minutes, so it can take a few minutes for a request to show up. The 5-minute and 15-minute shortcuts remain, with a notice about this delay. So:

* The most recent minutes of a chart can still grow when you refresh.
* A request you just made may take a few minutes to appear in Requests.
* Use the **Request ID** and the time shown to match a row, rather than waiting for it to show up at the top.

## When the panel is busy

Analytics has limits so that everyone gets a fair share:

* **Too many queries in a row.** Many consecutive queries from the same account can return `429 RATE_LIMIT_EXCEEDED`. `details.retry_after` says how many seconds to wait.
* **High-demand moments.** When demand is very high and no recent result is available for the period, the answer is `503 ANALYTICS_BUSY`, also with `details.retry_after`. The panel shows a countdown and tries again by itself.

When a recent result for the same period is available, the panel may show it instead of failing.

## What this does not affect

[Privacy](https://docs.vertracloud.app/web-analytics/privacy.md), the plan division in [History and plans](https://docs.vertracloud.app/web-analytics/history-and-plans.md) and your billing are unrelated to sampling.

Next: [History and plans](https://docs.vertracloud.app/web-analytics/history-and-plans.md).


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