In most cases, variable series are based on "raw" historical values of the series variable. These values are stored in the server database.
However, it's possible to build a chart those historical data points are based on a statistical channel.
To build such a chart:
| • | Make sure that a statistical channel exists for the series variable |
| • | Use a special statistics reference within series Expression |
Statistics Reference
The statistics reference has one of the following formats: {statistics/channel} or {statistics/channel#key}.
Once statistics reference is used inside series Expression, chart builder takes historical data from the channel named channel. This channel should be based on the series source variable.
If a key is specified, the statistical Dataset matching this key will be used as a source.
The following series parameters affect fetching statistical data:
| • | Aggregation. Series aggregation setting match statistical aggregation function those results will be used. |
| • | Type. Series type must match statistical channel's type. |
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Series expression may include only one statistics reference. Referring multiple channels not possible. |
Referring Other Fields from Statistics-Based Series Expression
Statistics-based series expression may also refer other fields of the source variable. However, such references have some important nuances:
| • | Statistical channel doesn't keep the original historical values of the variable. Therefore, any reference to the cells of source variable is resolved using current value of this variable. |
| • | If real-time history is enabled for a statistics-based series, the chart builder will merge statistical channel's expression and series' expression to generate new expression for building real-time data points. |