Error bars in Excel: standard and custom

This tutorial demonstrates how to create and utilize error bars within Microsoft Excel. You'll learn to quickly insert standard error bars, construct custom error bars, and even generate error bars of varying sizes reflecting individually calculated standard deviations for each data point.

Many find uncertainty unsettling, often associating it with insufficient data, flawed methodologies, or inadequate research. However, uncertainty isn't inherently negative. In business, it fosters preparedness for future challenges. In medicine, it sparks innovation and drives technological advancements. In science, uncertainty initiates the investigative process. Scientists, known for their quantitative approach, have devised methods to quantify uncertainty, calculating confidence intervals (or margins of error) and visualizing them using error bars.

Adding Error Bars in Excel (2013 and later)

Excel 2013 and subsequent versions simplify error bar insertion:

1. Select any part of your chart.

2. Locate the "Chart Elements" button adjacent to the chart.

3. Click the arrow beside "Error Bars" and choose your preferred option:

   • Standard Error: Displays the standard error of the mean for all data points, indicating the sample mean's likely deviation from the population mean.
   • Percentage: Adds error bars with a default 5% value; customize this percentage via "More Options."
   • Standard Deviation: Illustrates data variability—how closely data points cluster around the average. The default uses 1 standard deviation for all points.
   • More Options…: Enables specification of custom error bar values.

   

Selecting "More Options" reveals the "Format Error Bars" pane, allowing you to:

• Set custom values for fixed values, percentages, and standard deviations.
• Define direction (positive, negative, or both) and end style (cap or no cap).
• Create custom error bars based on your data.
• Modify error bar appearance.

For instance, to add 10% error bars, select "Percentage" and input "10" in the designated field:

Tips:

• To add standard error bars directly, select the "Error Bars" checkbox without choosing a specific option.
• To customize existing error bars, double-click them; the "Format Error Bars" pane will appear, enabling adjustments to type, color, etc.

Error Bars in Excel 2010 and 2007

Earlier Excel versions differ slightly:

1. Click the chart to activate "Chart Tools" in the ribbon.
2. On the "Layout" tab, within the "Analysis" group, click "Error Bars" and select an option.

Adding Custom Error Bars in Excel

While Excel's standard error bars suffice in many cases, you can also display your own calculated values:

1. Click the "Chart Elements" button.
2. Select "Error Bars" then "More Options…"
3. In the "Format Error Bars" pane, choose "Custom" under "Error Amount," and click "Specify Value."

4. A dialog box appears with fields for positive and negative error values. Enter your values (without curly braces or equals signs—Excel adds them automatically) and click "OK."

To omit positive or negative error bars, enter "0" in the corresponding field; do not leave it completely blank.

Creating Individual Error Bars of Different Lengths

Excel's built-in options apply a single value to all data points. To create error bars of varying lengths reflecting individual error calculations:

1. Input your error values (or formulas) into separate cells, ideally in the same column or row as your original data.
2. Use the "Custom" option in the "Format Error Bars" pane, specifying your range of error values for positive and negative error values separately.

Crucial Note: Completely clear the entry boxes before selecting your range to avoid errors.

The result will be individual error bars proportional to your calculated values:

Adding Horizontal Error Bars

Horizontal error bars are primarily available for bar charts, XY scatter plots, and bubble charts. For bar charts, they are the default. To add only horizontal error bars to other chart types, add error bars as usual, then delete the vertical error bars.

Error Bars for Specific Data Series

To add error bars to only selected data series, select that series, then use the "Chart Elements" button and "Error Bars" options.

Modifying and Deleting Error Bars

To modify existing error bars, use the "Format Error Bars" pane (accessible via double-clicking the error bars or via the "Chart Elements" button). To delete error bars, either uncheck the "Error Bars" box in the "Chart Elements" menu or right-click and select "Delete."

This comprehensive guide covers error bar creation and manipulation in Excel. We hope this helps!

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