How to create a Bell Curve in Excel
To teach you the process of making a bell curve in Excel, I have taken sample data of 10 students’ marks in a particular subject. The marks are out of 100.
1] First, you have to arrange the entire data in ascending order. For this, select the entire column of marks, click on the “Sort Filter” button on the toolbar and select the “Sort Smallest to Largest” option. After selecting this option, a popup window will appear on the screen with two options, “Expand the Selection” and “Continue with the Current Selection.” You have to select the first option as it will arrange the students’ marks in ascending order along with their names.
2] To create a bell curve in excel, we need three values, average, standard deviation, and normal distribution. Let’s calculate the average of the data first. For this, enter the following formula and press the “Enter” button: You can calculate the average in any cell, I have calculated it in B13 cell. Do note that you have to enter the correct cell address in the average formula. Here, cell B2 contains the first number and cell B11 contains the last number for the calculation of average.
The average of our data is 82. 3] Now, let’s calculate the standard deviation of the data. For this, you have to enter the following formula: Like mean, you can calculate the standard deviation in any cell, I have calculated it in B14 cell. Again, in this formula, B2 represents the data in the B2 cell, and B11 represents the data in the B11 cell. Please enter the cell address correctly.
The standard deviation of our data is 6.09918. This means that most of the students will lie in the range of 82 – 6.09918 or 82 + 6.09918. 4] Now, let’s calculate the normal distribution of the data. The normal distribution is to be calculated for each student separately. Therefore, I have written it in column C. Select the cell C2 (the cell just below the normal distribution cell) and enter the following formula, and press the “Enter” button: In the above formula, the $ sign indicates that we have put the respective cell to freeze and FALSE indicates the “Probability mass distribution.” Since the bell curve is not a continuously increasing curve, we have selected the function FALSE. The TRUE function indicates the “Cumulative distribution function” which is used to create graphs with increasing values.
5] Now, place your cursor at the bottom right corner of the selected cell (C2) and drag it to the last cell (C11). This will copy and paste the entire formula to all the cells.
6] Our data is ready. Now, we have to insert the bell curve. For this, first, select the marks and normal distribution columns and go to “Insert > Recommended Charts.”
7] Now, click on the “All Charts” tab and go to “XY Scatter > Scatter with Smooth Lines.” Here, select the “Normal Distribution” chart and click the “OK” button.
8] The bell curve is ready.
There are many customization options in the bell curve. You can set the minimum and the maximum values of X and Y-axes by clicking on them. For your convenience, I have listed the steps to change the values of the X-axis.
You can also show and hide different chart elements. For this, select the graph and click on the “Plus” icon. There, you will get a number of options. You can select and deselect any or all of them.
We have seen above that the shape of the bell curve is not perfect. This is because the difference between the values on the X-axis (marks of the students) is not the same. Now, we are creating one more bell graph with equally spaced values on the X-axis. You have to follow the same steps mentioned above in the article. See the below screenshot.
This is the perfectly shaped bell curve. In this article, we have explained the bell curve with both equally and unequally spaced values on the X-axis. Now, you can create a bell curve in MS excel. You may also like: How to make a Gantt chart in Excel.
