Use the Reference, and Trend line tools to visually reveal trends in your data set, and to make reasonable predictions about future values. These tools include:
Reference Line—A horizontal or vertical line drawn in the diagram to indicate a user defined computed value.
Trend line—A line connecting two or more data points representing a linear regression model of data. Generally, the trend line slants because it reflects the movement of a value's increase or decrease over time.
A Reference Line is a horizontal or vertical line drawn in the chart diagram to indicate a computed value. It is typically used to illustrate or compare a fixed value within a category of values. It can include an assigned statistical function (average, minimum or maximum). There can be several reference lines created for the same fact column having different statistical functions associated with each one. When the statistical function of a reference line is calculated, not only the data from current page, but also the data from all pages of a multi-page chart (or zoomed chart) are included. The category items that are hidden as a result of applying ‘Hide Items’ or ‘Focus on Item’ or ‘Drill Anywhere’ are not included.
Reference lines can be drawn on the top of visible graphic elements of a diagram (for example, bars or lines). By default the lines are drawn on the top. Reference lines can be shown wit ha text label, and reference line information in the legend. By default a reference line has a text label associated with it showing auto-generated text. This line. is set automatically and cannot be adjusted by a user.
This example shows a fact based reference line associated with an Amount Sales fact column assigned to the Average function.
The Stacked Bar, Stacked Area charts both allow axis-based and fact-based Reference lines. A single fact-bound Reference Line is drawn for summed stacked items.
A Pie chart cannot have any type of reference line.
The fact based reference line is always associated with a fact column. When the column is removed from the Chart data layout, the corresponding reference line is also removed. When the fact column is hidden or focused, the reference line is also hidden, or focused.
If the chart type is switched to another chart type, the Reference Lines is hidden. Switching back to the original chart type restores the lines.
Reference Lines and Chart Types
The Stacked Bar, Stacked Area charts both allow axis-based and fact-based Reference lines. A single fact-bound Reference Line is drawn for summed stacked items. A Pie chart cannot have any type of reference line. The fact based reference line is always associated with a fact column. When the column is removed from the Chart data layout, the corresponding reference line is also removed. When the fact column is hidden or focused, the reference line is also hidden, or focused. If the chart type is switched to another chart type, the Reference Lines is hidden. Switching back to the original chart type restores the lines.
Adding and Modifying Reference Lines
To add a reference line, select a chart item that represents a data fact and on the shortcut menu, select Add Reference Line.
To modify a reference line:
Double-click the reference line.
The Reference Properties dialog box is displayed.
Select Fixed to assign an axis based reference line, or a fact item from the Fact drop-down.
To assign a statistical function to a fact based reference line, select a function from the Function drop-down list.
Enable Show in legend to show the reference line in the legend.
Enable Show label to show the reference line label.
For more information about general reference lines, see Reference Line General Properties .
Select the Label Format tab to select any label properties.
For more information about reference line label formats, see Reference Line Label Format Properties .
Trend lines are used to track trends in a data series graphically. Interactive Reporting supports trend lines modeled after linear regression analysis. Generally the trend line is represented as a slanted line that crosses the diagram. For example, the trend line can demonstrate an increase or decrease of values over time. It may be accompanied with the calculated goodness of fit (R-squared) value.
Trend lines can be layered on top of the chart graphics (or Z axis for 3 D charts), or positioned to the background. When data is processed to create the trend line, facts from all pages of the chart are included. Chart items hidden or focused explicitly by the user are not included.
Trend lines are always fact based, and only one trend line can be associated with a single fact column. In Scatter and Bubble charts, the trend line is bound to the data series.
Trend lines should be used primarily with two dimensional perspective, but are supported with a three dimensional (3D) perspective. If they are used with a 3–D perspective, several parallel lines are drawn along the Z-axis together with graphical data.
Trend lines can be added to most chart type including stacked charts (Bar and Area). The value of each stack is included when the trend equation is calculated. When the separate stackables of a full bar belong to different facts, then a single trend for all facts is drawn. The sum of separate facts (either positive or negative) is included when calculating the trend line equation.
Trend lines are most effect in Scatter, Bubble and Time Aware charts.
A trend line with a single category on the X axis is preferable. In cases where there are multiple categories on the X axis, it might be difficult to analyze the trend if the categories are unrelated.
Pie charts cannot have trend lines.