Trend and Forecasting

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The Trend and Forecasting function calculates a regression line or line of best fit. When applied to a time series, it can forecast future values.

This function can be used with a measure and date/time values, or with two measures where each is typically plotted along a separate chart axis.

Trend and Forecasting
Trend and Forecasting

There are four regression functions available:

1. Syntax

Trend and Forecasting:

TRENDFORE(d0,d1,s0,s1,s2)

Upper Band Error:

TRENDFOREUPPER(d0,d1,s0,s1,s2)

Lower Band Error:

TRENDFORELOWER(d0,d1,s0,s1,s2)

Axis:

TRENDFOREAXIS(d0,d1,s0,s1,s2)

2. Input

The Trend and Forecasting functions require the following input series:

  • d0 - Trend Axis values - The set of values on the trending axis (e.g. datetime axis).
  • d1 - Input data values - The set of historical data values to be used in the Trend and Forecasting formula.

3. Parameters

  • s0 - Regression Type - The type of regression function used by the Trend and Forecasting formula. Available choices include:
    • 0 - Linear (default)
    • 1 - Exponential
    • 2 - Logarithmic
    • 3 - Power
  • s1 - Regression Degree - The degree used by the regression function in calculating the Trend and Forecasting formula. Default value is 2.
  • s2 - Forecasting Period - The length of the forecasted data series as returned by the Trend and Forecasting formula. Available choices include:
    • 0 - No Forecast
    • 1 - Tenth Input
    • 2 - Quarter Input
    • 3 - Half Input (default)
    • 4 - Full Input

4. Output

The Trend and Forecasting functions generate the following outputs:

  • Trend and Forecasting - The Trend and Forecasting result set.
  • Upper Band Error - The upper error boundary based on standard deviation and the forecasting error.
  • Lower Band Error - The lower error boundary based on standard deviation and the forecasting error.

5. Examples

5.1. Trend and forecast on a time series

This example adds a trend line including a forecast to a line chart.

With a measure and time dimension hierarchy displayed in a chart like the following:

Line chart displaying a measure changing over time
Line chart displaying a measure changing over time

You can quickly add a trend line by choosing Re-Visualize in the toolbar, then Add Trend Line.

Choose the Add Trend Line recommended option
Choose the Add Trend Line recommended option

This adds a formula measure that uses the TRENDFORE function with the default forecasting settings, visualized as a new line series.

Chart with trend and forecast
Chart with trend and forecast

You can now edit the formula if you choose to.

Trend line formula
Trend line formula

5.2. Linear regression on scatter plot

This example shows how to add a regression line, or line of best fit to a scatter plot.

With a scatter plot chart displaying two measures grouped by one or more hierarchies:

A scatter plot chart
A scatter plot chart

You can quickly add a trend line by choosing Re-Visualize in the toolbar, then Add Trend Line.

Choose the Add Trend Line recommended option
Choose the Add Trend Line recommended option

This adds a formula measure that uses the TRENDFORE function, visualized as a new line series.

Scatter plot with trend line
Scatter plot with trend line

You can now edit the formula if you choose to.

Regression line formula
Regression line formula

6. Notes

  • The forecast will only go ahead in time as far as the time dimension's end date.

7. See also

 

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