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Error Bars in Excel
Error bars in excel basically represents the variability of data and are used on the graph to indicate the error in the measurement. They give a general idea of how accurate a measurement is. In other words, it represent how far from the reported value the true value might be. Error bars often represents one standard deviation of uncertainty.
They also suggest the goodness of fit of a given function i.e. how well the function determines the data. If the added error bar in excel does not overlap, then data for one group is different from another. If the error bars overlap, then data for one group is not different from the other.
How to Add Error Bars in Excel? (Step by Step)
As data, we have taken three different species i.e. Red maple, Sugar maple, and Black maple and their mean width. We have taken a line graph for the same.
Step 1. The data is selected and from the Insert tab, the line graph is selected.
Step 2. Clicking the line graph option we get the following line graph.
Step 3. The excel error bars option can be found under the layout tab under the analysis group. Following screenshot shows the same.
Step 4. There are various error bars options available.
Step 5. Error bars with standard error. Standard error i.e. SE is basically the standard deviation of the sampling distribution of a statistic. The magnitude of SE helps in giving an index of the precision of the estimate of the parameter. The standard error is inversely proportional to the size of the sample. This means that smaller the sample size, it tends to produce greater standard errors.
In the below screenshot, the error bars with standard error is given. All the data points in the series display the amount of error in the same height for Y error bars and the same width for X error bars.
From the below screenshot, it can be seen that the straight line is drawn from the minimum of the maximum value i.e. Red Maple overlaps with the outermost value of the species Black Maple. This signifies that the data for one group is not different from the other.
Step 6. Error bars with the percentage
It uses the percentage that is specified in the percentage box for calculating the error amount for each data as a percentage of the value of that particular data point. The Y error bars and X error bars are based on a percentage of the value of the data points and vary in size as per the percentage value. By default, the percentage is taken as 5%.
The default 5% value can be seen from the More data bars options given in the screenshot below.
Step 7. Error bars with the standard deviation
Error Bars with the Standard deviation is the average difference between the data points and their mean. Usually, a one-point standard deviation is taken into consideration while creating the error bars. The standard deviation is used when the data is normally distributed and the pointers are usually equidistant to each other.
A line drawn on the maximum data point i.e. Red maple coincides with the maximum error point of black maple. This signifies that the data for one group is not different from the other.
#2 – Add Custom Error Bars in Excel
Apart from the three error bars i.e. error bars with standard error, error bars with standard deviation and error bars with percentage, custom error bars can be also made.
The minus display basically is the error to the lower side of the actual value. Just click on the minus tab.
Similar to minus, the plus can be also taken which represents the error to the upper side of the actual value. Just click on the plus tab.
We can also visualize the error bars without the cap. In the vertical error bars tab, we need to click or select direction as both an end style as no cap.
Things to Remember about Error Bars in Excel
- The error bars in excel as the graphical representation that helps in visualizing the variability of data given on a two-dimensional framework.
- Error bars in excel help in indicating the estimated error or uncertainty for giving a general sense of how accurate a measurement is.
- The accuracy is understood by the marker drawn over the original graph and its data points.
- The excel error bars are used to display with the standard error, standard deviation or with the percentage value
- Error bars in excel usually by drawing cap-tipped lines extending from the center of the plotted data point.
- The length of the error bars usually helps in revealing the uncertainty of a data point.
- Depending on the length of the error bars, the error can be estimated. A short error bar shows that the values are more concentrated directing that the average value that is plotted is more likely to be reliable. Along the error bar, on the other hand, indicate that the values are more spread out and are less likely to be reliable.
- Error bars in excel can be customized through more error bars option
- In the case of skewed data, the length on each side of the error bars would be unbalanced.
- The error bars in excel usually run parallel to the quantitative scale axis. This means that the error bars can be visualized either horizontally or vertically depending on whether the quantitative scale is on the X-axis or on the Y-axis.
You can Download this Error Bars Excel template here – Error Bars Excel Template
This has been a guide to Error Bars in Excel. Here we discuss how to Add Error Bars in Excel (standard, with standard deviation, percentage error, and Custom error bars) along with practical examples and downloadable excel template. You may learn more about excel from the following articles –