Error bars in charts you create can help you see margins of error and standard deviations at a glance. They can be shown on all data points or data markers in a data series as a standard error amount, a percentage, or a standard deviation. You can set your own values to display the exact error amounts you want. For example, you can show a 10 percent positive and negative error amount in the results of a scientific experiment like this:

You can use error bars in 2-D area, bar, column, line, xy (scatter), and bubble charts. In scatter and bubble charts, you can show error bars for x and y values.

## Add or remove error bars

1. Click anywhere in the chart.

2. Click the Chart Elements button next to the chart, and then check the Error Bars box. (Clear the box to remove error bars.)

3. To change the error amount shown, click the arrow next to Error Bars, and then pick an option.

• Pick a predefined error bar option like Standard Error, Percentage or Standard Deviation.

• Pick More Options to set your own error bar amounts, and then under Vertical Error Bar or Horizontal Error Bar, choose the options you want. This is also where you can change the direction, end style of the error bars, or create custom error bars.

Note: The direction of the error bars depends on the type of chart you’re using. Scatter charts can show both horizontal and vertical error bars. You can remove either of these error bars by selecting them, and then pressing Delete.

## Review equations for calculating error amounts

People often ask how Excel calculates error amounts. Excel uses the following equations to calculate the Standard Error and Standard Deviation amounts that are shown on the chart.

This option

Uses this equation

Standard Error

Where:

s = series number

i = point number in series s

m = number of series for point y in chart

n = number of points in each series

yis = data value of series s and the ith point

ny = total number of data values in all series

Standard Deviation

Where:

s = series number

i = point number in series s

m = number of series for point y in chart

n = number of points in each series

yis = data value of series s and the ith point

ny = total number of data values in all series

M = arithmetic mean

Tip: You can remove error bars immediately after you add them to the chart by clicking Undo on the Quick Access Toolbar or by pressing CTRL+Z.

## Express errors as a percentage, standard deviation, or standard error

1. In the chart, select the data series that you want to add error bars to.

For example, in a line chart, click one of the lines in the chart, and all the data marker of that data series become selected.

2. On the Chart Design tab, click Add Chart Element

3. Point to Error Bars, and then do one of the following:

Click

To

Standard Error

Apply the standard error, using the following formula:

s = series number I = point number in series s m = number of series for point y in chart n = number of points in each series y is = data value of series s and the I th point n y = total number of data values in all series

Percentage

Apply a percentage of the value for each data point in the data series

Standard Deviation

Apply a multiple of the standard deviation, using the following formula:

s = series number I = point number in series s m = number of series for point y in chart n = number of points in each series y is = data value of series s and the I th point n y = total number of data values in all series M = arithmetic mean

## Express errors as custom values

1. In the chart, select the data series that you want to add error bars to.

2. On the Chart Design tab, click Add Chart Element, and then click More Error Bars Options.

3. In the Format Error Bars pane, on the Error Bar Options tab, under Error Amount, click Custom, and then click Specify Value.

4. Under Error amount, click Custom, and then click Specify Value.

5. In the Positive Error Value and Negative Error Value boxes, type the values that you want for each data point, separated by commas (for example, 0.4, 0.3, 0.8), and then click OK.

Note: You can also define error values as a range of cells from the same Excel workbook. To select the range of cells, in the Custom Error Bars dialog box, clear the contents of the Positive Error Value or Negative Error Value box, and then select the range of cells that you want to use.

1. In the chart, select the data series that you want to add up/down bars to.

2. On the Chart Design tab, click Add Chart Element, point to Up/Down Bars, and then click Up/down Bars.

Depending on the chart type, some options may not be available.