Trend lines, forecasts and reference lines
Add a trend, a forecast, a comparison or a target line to a chart, and know exactly how Halo works each one out.
The chart editor's Analysis section adds trends, forecasts, comparisons and target lines to column, bar, line, area and combo charts. Halo keeps the math simple on purpose, so you can explain any line on a chart to the person who asks.
A six-month forecast with its band, a straight trend line, and a goal as a reference line.
Add a trend line
Open Analysis and choose a Trend:
Straight line fits a least-squares line through the values.
Moving average averages each value with the ones before it. Over periods sets how many, from 2 to 60, and defaults to 3. The line starts once the first window fills.
Trends draw dashed, one per series, and appear in the legend. They work on upright charts, so not on a sideways bar chart or a combo with a Second axis.
Add a forecast
Forecasts need a date on the axis, grouped by a time grain. Stacked series, sideways bars and combos with a Second axis don't forecast. Neither do hour or minute grains, and a forecast needs at least three values to start from.
In Analysis, set Forecast periods to how far ahead to look, up to 60.
Choose a Forecast method: Seasonal when it can or Straight line.
The estimate continues the line, dashed, with a band around it that widens with distance. Hovering labels each value as an estimate.
| Method | How it works |
|---|---|
| Seasonal | Each future period repeats the same period one season back, plus the average change from one season to the next |
| Straight line | The overall slope, continued from the last value |
Seasonal when it can uses seasonal when there are two full seasons of history, and a straight line otherwise. A season is a year of months, weeks or quarters, or a week of days.
In the table view, a chart without a breakdown lists forecast rows after the real ones, marked in an Estimate column.
Compare with an earlier period
On a time series without a Breakdown, Compare with adds an earlier period for the first measure: Previous period is the same length just before, and Same period last year shifts the dates back a year. Bar charts, sideways charts and combos with a Second axis don't compare. On a scorecard, the same choices are under Compare.
Both need a date range filter, on the chart or from a report. Without one, the chart says what to add. See Dates, time zones and fiscal calendars.
Add a reference line
A reference line is a horizontal line across the plot, such as a target or an average. Sideways bars draw it upright. A chart can have up to five.
In Analysis, choose Add reference line.
Choose its kind:
Value, a number you type, such as a target.
Average, Median, Lowest or Highest, worked out from what the chart shows, so they move with filters.
Give it a label, which shows on the line with its value.
Computed lines read the chart's first series.
Track a target over time
For a target that changes by period, set a goal. New goal from this chart, in a chart's actions menu, starts one from the chart's measure. Then pick it under Compare with goal in the chart's Goal section, and the chart draws it. See Compare a chart with a goal.
Mark values with rules
Column and bar charts can color bars that meet a rule, such as orders below a floor. See Color rules.
Using a target from a formula
A reference line's value is fixed in the chart. If people should try different targets, add a parameter and use it in a calculated field, such as SUM([Revenue]) / @target.