How to show the critical difference (CD)/ least significant difference (LSD) in a Microsoft Excel Chart

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Researchers and Scientists usually need to show Least Significant Difference (LSD) or Critical Difference (CD) within the graphics to explain the difference between effects of different treatments. It is easy to show the standard errors in charts or graphs using Microsoft Excel program but difficult to show the LSD since Excel program has options only for standard error but not for LSD. However, it is desirable to show the CD or LSD in the chart to explain variation in data due to treatment effect. When test of significance indicates that difference between different treatments is non-significant it is enough to show the standard errors in the chart. In case of significant treatment difference, depicting the treatment difference with standard error does not convey the exact meaning. LSD can be shown in a graph easily following few simple steps as shown below. Sometimes reviewers ask authors to show CD or LSD as a line or a bar depending on the style of data presentation.

Step 3. In the blank row (between treatment and LSD row), put a value higher than the maximum data value shown for production. Here we placed 22 (Max. value=17.2). What value would be better? You'll learn by experience.

Step 4.  Click on the chart and select the data (Include the blank row which you have just filled with value 22. Chart will show straight line for this data series in straight line chart but a bar column in bar chart. Click on this data series and change bar chart to line chart.

Step 5. Now right click on the added line and click "format data series".

Now select "Y Error Bar" and select the custom button.

Now click in the blank space of "+" button, enter the LSD vales for all the years and press the enter button. Repeat the same for "-" button.

Caution: If you input LSD value manually, it may show the same value. Instead providing LSD value manually, it is better to click on the icon ( beside data box) and select the LSD range from the table. In case of manual entry of LSD value, all the values will be same.

Step 6. This is your last step. Right click on data series and select pattern.

Under the line menu, click "none" and also select "none" under the marker value.

This procedure is for Office 2003. You can show a bar column in place of line using Office 2007.


© 2009 C V Singh

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