A data series is simply a set of data that gets displayed on a chart. For example, a pie chart or serial chart showing lines, columns, bars, or areas relies on a series of data to render its display. In the case of the serial chart, more than one series can be displayed at a time.
You can think of a series as an array of name-value pairs. Each instance of a name-value pair in the array is a data point. When plotted on a chart, each data point has a shape. For example, in a pie chart the shape of each data point is a wedge. In a serial chart showing columns, each data point is a column.
The data sources for dashboard elements are layers, and each layer has one or more columns of attributes. To plot on a chart, a series from the layer's underlying data must be created. There are three options to do this: Grouped Values, Features, and Fields.
The grouped values option relies on data aggregation to create a series. From the raw data, each data point in the series represents a summary statistic (e.g. count, sum, average, minimum, maximum, or standard deviation) grouped into categories using a field's unique values in the input layer. For all summary statistics except count, a field from which to gather the summary statistic must also be provided. In the following example, the Condition field is used to group the raw data into categories. The count of each unique Condition is then calculated and plotted on the chart.
When grouping values into categories on a serial chart, it's possible to specify a 'split by' field. In this scenario, the input data is split into multiple data series (i.e. one series for each unique value in the split by field). Using the same data as the above example, you can produce a chart like the one below by categorizing the data based on the values in the Condition field, but splitting them into multiple series based on the Corroded field.
This is the simplest option, and causes the chart to draw the fastest. Each feature or row of data represents a data point in the series. No summary statistic must be calculated. One field is identified as the category or name field, while another is identified as containing the value to plot. In the following example, the Region field represents the categories and the Incidents field represents the value to plot.
In this scenario, one or more numeric field names are specified to represent the categories. For each field or category, a summary statistic is calculated to create a data point. In the following example, the CY2017, CY2016, and CY2015 fields represent the categories. The sum of all rows is plotted on the chart.