Time, freshness, and accuracy
Reports describe a selected period, a set of identities, and the data currently available to the engine. Understanding those three choices makes comparisons and counts easier to interpret.
Calendar ranges and rolling windows
| Range | Meaning | Use it for |
|---|---|---|
| Today, yesterday, last 30 days | Calendar days in the report's time zone | Website and business reports |
| This month or this year | A calendar period | Monthly or annual comparisons |
| Last 30 minutes or 12 hours | A rolling duration ending now | Recent activity and monitoring |
| From and to | An explicit range | A campaign, release, or investigation |
DateRange.LastDays(30) includes today by default. An absolute date-time range includes its start and excludes its end. Calendar-day ranges include the selected end day.
Day, week, month, and year buckets follow the query's time zone. Minute and hour buckets are aligned in UTC. The engine uses its configured reporting time zone unless the request supplies another.
Comparisons
A previous-period comparison uses a preceding period of the corresponding length. A previous-year comparison follows the corresponding calendar period in the prior year.
Keep the site, filters, and time zone consistent when comparing reports. A different audience or calendar can explain a change without any change in overall activity.
Report freshness
Tracking and reporting can run together. The engine processes new activity in the background and updates reports automatically; no explicit flush is required before normal queries.
The default aggregate update interval is two seconds. Dashboard refresh settings add their own delay, so several visits may appear together in the next update.
The live visitor count describes a recent sliding window. It can decrease when a visitor's last event leaves that window, even while total page views increase.
Unique visitors
A visitor count merges distinct identities across the selected range. The same identity can appear in several page or source rows; use report totals rather than adding row counts.
Anonymous identity rotates daily by default. A person visiting on multiple days can therefore count as multiple identities in a multi-day report. Explicit IDs or persistent anonymous hashing support cross-day recognition.
At default precision, unique-count sketches are exact up to 4,096 identities per row and have about 0.8% standard error above that range.
Numeric metrics and coverage
Averages, sums, and percentiles describe different aspects of a measurement. A percentile is a distribution estimate, not an average. Its accuracy limits are documented in the query reference.
Accuracy and coverage are separate: a report may accurately aggregate the data it has while some requested history has expired. Plan.Warnings and Plan.IsComplete describe coverage concerns.
A null metric means it is unavailable or does not apply to that report context. Treat it differently from a measured zero.