Add trendlines and error bars to a measurement chart

Quick answer

Select the measurement series in a supported two-dimensional, non-stacked chart. Use Chart > Add chart element > Add trendline for a linear fit, and Error bars > More for a fixed plus/minus uncertainty. Check the formula and intervals separately: a fitted trend and an error bar describe different things.

Prepare a suitable chart and fixture

This guide targets paid PlanMaker 2024 on Windows with the English ribbon. Begin with an ordinary two-dimensional, non-stacked line chart containing one measurement series. The task here is enhancing that chart, not building every chart option from scratch. If necessary, use the separate ordinary chart workflow as background while checking your own version’s controls.

Use a disposable source block with A1 Position, B1 Measurement, A2:A5 equal to 1, 2, 3, 4 and B2:B5 equal to 3, 5, 7, 9. The chart should use A2:A5 as its four category labels and B2:B5 as the single measurement series. Do not plot Position as an extra measurement series.

The positions are equally spaced and deliberately match the category indexes 1 through 4. That makes the linear fit meaningful for this simple line-chart exercise. A category chart is not a substitute for an XY scatter plot when actual x-values are irregularly spaced. For that separate task, see paired XY measurements, with its own version scope.

The expected line is y=2x+1. The supplied measurement uncertainty is an illustrative fixed ±0.5 units, not a confidence interval calculated from repeated experiments. Write that distinction in a nearby note before adding the visual elements.

Add a linear trend to the correct series

1. Click a data point once to select the entire measurement series. Clicking again can select only that point, so check the selected object before continuing.
2. Choose Chart > Add chart element > Add trendline and select the linear type.
3. Select the trendline, right-click, and choose Trendline: Properties, or double-click it.
4. In its trendline settings, verify Type is Linear and Based on series refers to the measurement series.
5. Enable Show formula in chart. Leave any forced Crossing point unset and leave forecast extension at zero for the initial test.

For the fixture, the expected slope is 2 and intercept 1, because each step raises the measurement by two units and the value at position 1 is 3. Formula text may use rounded formatting or a different term order; check the coefficients rather than requiring an identical string.

Do not force the intercept to zero simply to obtain a neat-looking line. That would impose a different model and would not match this fixture. A perfect fit here reflects deliberately constructed numbers, not proof that a real process is predictable.

Add the fixed error magnitude

Select the measurement series and right-click Series: Properties. Open the Error bar Y tab. Alternatively, use Chart > Add chart element > Error bars > More to reach the additional settings.

In Display, choose Plus and minus. In Value, choose Fixed and set the magnitude to 0.5, using your locale’s decimal separator. Choose the end-cap appearance you prefer under Show as, then confirm.

The expected intervals are 2.5–3.5, 4.5–5.5, 6.5–7.5 and 8.5–9.5. Each bar extends 0.5 above and 0.5 below its own measured value, for an overall span of 1. A 50% setting would create much larger and varying intervals, so inspect the selected mode rather than judging only the visual length.

These bars are a supplied tolerance illustration. They do not automatically represent standard errors, sampling uncertainty or a particular confidence level. Label the chart accordingly so a reader does not infer a statistical claim you did not calculate.

Change one measurement and one display setting

Change B5 from 9 to 10. The best-fit line for positions 1,2,3,4 and values 3,5,7,10 is y=2.3x+0.5. This follows from a mean x of 2.5, mean y of 6.25, cross-deviation sum 11.5 and x-deviation square sum 5. The last fixed error interval becomes 9.5–10.5, while the first three intervals remain unchanged.

Inspect the chart after the source change and confirm both independent effects: the trend coefficients change, while the fixed magnitude remains 0.5. If the chart does not reflect the new value, inspect its actual source range before altering the trendline type.

Next change only the fixed error magnitude to 1. The last interval becomes 9–11, but the measured points and fitted coefficients should not change. Restore the magnitude to 0.5 and B5 to 9, then confirm y=2x+1 and the original intervals.

Save, remove and troubleshoot

Save a PMDX practice copy and reopen it. Inspect the series selection, trendline type and error-bar magnitude, not only the saved image. For exported images or PDFs, check that the formula and uncertainty note remain readable and are not clipped; static output cannot prove the editable chart settings survived.

If an option is missing, first check the chart type. The documented features are limited to supported two-dimensional types, and trendlines are not available on stacked charts. If the wrong series receives the trend, correct Based on series. To remove one trendline, select that line and delete it; use the broader Remove all command only when you intend to remove the chart’s trendlines.

No native chart, regression engine or export was executed during authoring. The coefficients above were independently calculated from the fixture.

Official references

See adding trendlines, trendline settings, adding error bars, and series properties.