Working with Line Charts

About Line Charts

A line chart displays data by using a line that connects the data values. If you assign multiple measures to a line chart, then you can create separate Y axes for each measure.

Data Roles for a Line Chart

The basic data roles for a line chart are categories and measures. You can assign one category only, and the category values are plotted on the category axis. You can assign many measures, and the measure values are plotted on the response axis. If the line chart contains no measures, then the frequency of the category values is plotted on the response axis.

In addition to the basic data roles, you can assign these roles:

Group

groups the data based on the values of the category data item that you assign. A separate line is created for each data value.

Note: Grouping is not available if you assign multiple measures to the visualization.

Lattice columns

creates a lattice of charts with a column for each value of the category data item that you assign.

Lattice rows

creates a lattice of charts with a row for each value of the category data item that you assign.

Forecasting

enables forecasting for the line chart. Forecasting estimates future values for your data based on statistical trends.

Note: Forecasting is available only if a date or datetime data item is assigned to the visualization.

Underlying factors

if forecasting is enabled, adds additional measures to the forecast as underlying factors. The forecasting model evaluates the additional measures to determine whether they contribute to the accuracy of the forecast. If the additional measures do not increase the accuracy of the forecast, then they are not used. If the additional measures do increase the accuracy of the forecast, then the forecast line is adjusted, and the confidence bands are narrowed.

The measures that you add as underlying factors can also be used in a scenario analysis.

Note: Underlying factors are available only if your line chart contains a single measure in the Measures role.

Specify Properties for a Line Chart

On the Properties tab, you can specify the following options:

Name

specifies the name of the visualization.

Title

specifies the title that appears above the graph.

Note: The Title option is disabled if you select Generate graph title.

Generate graph title

specifies that the graph title is generated automatically based on the data items in the visualization.

Show grid lines

displays grid lines for each tick on the response axis.

Frequency

specifies whether the frequency is displayed as a count (Count) or as a percentage (Percent).

Note: The frequency values are based on the data that is shown in the visualization (after filters and other data selections have been applied).

Note: This option has no effect if a measure is assigned to the visualization.

Measure layout

specifies whether the measures share a single response axis (Shared axis) or have separate response axes for each measure (Separate axes).

Note: The Measure layout option is disabled if your visualization contains exactly one measure.

Overview

specifies whether the chart overview is enabled.

Show markers

shows markers for the data points in the visualization.

Show data labels

shows the data values as text in the visualization.

Note: You can always view a data value as a data tip when you position the cursor over a data value.

Thin data labels

removes data labels as necessary to avoid overlap. The thinning algorithm retains the labels for local high points and low points on the line chart.

Rotate axis labels

displays the category labels at an angle.

Reference Lines

adds reference lines to the visualization. To create a reference line, click the Create new reference line button

, and then specify the parameters for the line in the New Reference Line window.

The name of each reference line appears below the Reference Lines option. You can edit or delete your reference lines by using the icons next to each name.

Duration (if forecasting is enabled)

specifies the number of data intervals to forecast.

Note: This option is available only if forecasting is enabled for the visualization.

Confidence (if forecasting is enabled)

specifies the degree of confidence for the confidence band. The default value is 95%.

Sort Data Values

By default, for category data, a line chart is sorted in descending order by the value of the first measure. To change the sorting, right-click on the data item that you want to sort on, and then select Sort and select a sorting method.

Note: If the visualization contains a rank, then, by default, the data is sorted based on the values of the rank.

Note: Sorting is not available if a datetime data item is assigned to the Category role.

Forecasting

About Forecasting

Forecasting uses the statistical trends in your data source to predict future data values. Forecasting is available only if a date or datetime data item is assigned to the visualization.

In addition to the predicted future data values, the forecast displays a confidence band. For more information, see Forecasting.

Enable Forecasting

To add forecasting to a line chart, select Forecasting on the Roles tab.

Note: The line chart must contain a date or datetime data item to apply forecasting.

On the Properties tab for the line chart, you can adjust the number of data values to predict by using the Duration option. You can specify the degree of confidence for the confidence band by using the Confidence option.

On the Roles tab, you can add additional measures to the forecast as Underlying factors. The forecasting model evaluates the additional measures to determine whether they contribute to the accuracy of the forecast. If the additional measures do not increase the accuracy of the forecast, then they are not used. If the additional measures do increase the accuracy of the forecast, then the forecast line is adjusted, and the confidence bands are narrowed.

Note: Underlying factors are available only if your line chart contains a single measure in the Measures role.

The measures that you use as underlying factors can also be used in scenario analysis and goal seeking. For more information, see Working with Scenario Analysis and Goal Seeking.