Guide to Error Bars in Grapher

Enhance your graphs with multi-parameter-defined error bars to represent data measurement precision. Visualize error envelopes accurately by connecting and filling between them. Demonstrate transparency to your stakeholders, allowing your data to speak clearly. Tailor the error bar type to match your data display preferences.

Add error bars to a plot in Grapher

Follow these steps to add error bars to a plot:

1. In the Object Manager, select your plot.
2. In the Property Manager, click the Error Bars tab.
3. Change the Direction to Vertical, Horizontal, or Vertical and Horizontal.
4. If you wish for the error bars to be drawn in front of the plot, uncheck Draw behind plot.
5. Set the error bar properties in the General section. If you have selected Vertical and Horizontal, the properties being displayed in the General section are for the direction selected in the Properties to edit field.

Line Scatter plot with positive and negative error bars.

Connect error bars and fill between them

1. Select your line plot.
2. On the Error Bars page in the Property Manager, set the desired Direction of your error bars, and then set the type of error bar.
3. Once your error bars are displaying, check the box next to Connect points.
4. On the Line page, expand the appropriate Connection Line section in the Error Bar Line Properties section, and edit the line properties.
5. On the Fill page, expand the appropriate Connection Line section, and edit the fill properties.

Line Scatter plot with displaying fill between connected error bars.

Error bar types

You can set the Error Bar type through the Error Bars tab in the Properties Manager. The choice of error bar type depends on the specific information you want to convey in your data visualization. Different error bar types provide different insights into the data's distribution and variability, so selecting the most appropriate one depends on the context and goals of your analysis.

• Read from Data Variable

  • Use when you have custom error values calculated in your worksheet.
  • Helpful for displaying error bars when both vertical and horizontal error bars are needed.

• Average Value Only

  • Choose when you want to display the average Y value for each X value with vertical error bars or the average X value for each Y value with horizontal error bars.
  • Useful when you want to show a representative or central tendency value along with your data points.

• Sample Standard Deviation

  • Opt for this option when you want to display the sample standard deviation of Y values for each X value with vertical error bars or X values for each Y value with horizontal error bars.
  • Provides insight into the variability of data points around the mean, especially when dealing with a sample of data.

• Population Standard Deviation

  • Select when you want to show the population standard deviation of Y values for each X value with vertical error bars or X values for each Y value with horizontal error bars.
  • Useful for representing variability when you have data for the entire population, not just a sample.

• Standard Error of the Mean

  • Use when you want to display the standard error of the mean of Y values for each X value with vertical error bars or X values for each Y value with horizontal error bars.
  • Particularly valuable when you want to convey the precision of the mean as an estimate of the true population mean, especially with large datasets.

To learn more about error bars in Grapher, please see the Grapher Help entry Error Bars.

Updated March 2023