You can configure charts to show statistics that provide quantitative data for the trend. These statistics allow you to view process tendencies at a glance so that you can better understand what the data means.
Statistical values are computed using historical and real-time data from any of the historian data sources (DeltaV Continuous Historian, Advanced Continuous Historian, and Enterprise PI). The statistics include the highest and lowest process values over a given time span (Maximum and Minimum), an average process value (Time Average), and a totalized value for what is happening in the trend (Total). Only the data plotted in the chart is used to compute the statistics. For example, when compression is set to Automatic, compressed data is used to compute the statistics. When compression is set to None, raw data is used to compute the statistics. For a running trend, chart statistics update dynamically. When the operator selects a particular time span (zoom in/out and zoom back all), the statistics update to show values for the new time span.
In the graph, Minimum, Maximum and Time Average statistics are represented by markers that, by default, match the color of the trend line. You can change the color of the Min and Max markers in the Configure Trend dialog. The legend shows the statistics as numerical values, unless a trend returns a string value. String values are represented as dashed lines in the legend.
