The bell curve or standard deviation graph is used to visualise the spread of data. Excel is powerful tool to create graphs and visualise data and it can be used to create the bell graph.
The standard deviation tells how much the data is clustered around the mean of the data. Lower standard deviation tells that the data is less spread and higher standard deviation tells that data is more spread.
Let’s say, I have productivity data of my 77 employees. Now to make the Standard Deviation graph, we will need probability distribution of each number in data. To calculate probability distribution in excel, we will need mean and standard deviation.
Preparing Data For Standard Deviation Chart (Graph) or say Bell Curve
Now, to plot a bell graph or say standard deviation chart of this, we first need to calculated the Mean of data, and standard deviation in excel.
To calculate mean, use AVERAGE function.
To calculate standard deviation of entire population use STDEV.P
Now, since we have, mean and Standard Deviation, we can calculate Normal distribution.
Use NORM.DIST function.
Copy this formula down the cells.
Since we need to calculate probability distribution of each employee, we give absolute reference of A2 and we lock MEAN and STANDARD DEVIATION.
Plotting Standard Deviation Chart in Excel
Now since we have every ingredient for preparing our Deviation curve, we will use excel charts to get the bell curve.
Follow these steps:
And you will have the bell curve or say standard deviation chart.
Since we have a large standard deviation, the standard deviation is wider. If we reduce the standard deviation, the bell curve will be more lean toward the mean of data. You can see that, when we reduce the standard deviation, the curve get more lean.
So yeah guys, using this method, you can easily create a bell curve or standard deviation graph/chart in excel. The standard deviation curve will be slim if SD is low, higher standard deviation value will lead to wider bell curve.
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