Normal distribution graph in excel is used to represent the normal distribution phenomenon of a given data, this graph is made after calculating the mean and standard deviation for the data and then calculating the normal deviation over it, from excel 2013 versions it has been easy to plot the normal distribution graph as it has inbuilt function to calculate the normal distribution and standard deviation, the graph is very similar to the bell curve.
Excel Normal Distribution Graph (Bell Curve)
A normal distribution Graph is a continuous probability function. We all know what probability is, it is a technique to calculate the occurrence of a phenomenon or a variable. A probability distribution is a function which is used to calculate the occurrence of a variable. There are two types of probability distributions, Discreet and continuous.
The basic idea of what is a normal distribution is explained in the overview above. BY definition, a normal distribution means how evenly the data is distributed. A continuous probability distribution is used to calculate real-time occurrences of any phenomenon. In mathematics the equation for a probability distribution is as follows:
Seems so complex right? but excel has made it easier for us to calculate normal distribution as it has a built-in function in excel of the normal distribution. In any cell type the following formula,
It has three basic factors to calculate the normal distribution in excel:
- X: X is the specified value for which we want to calculate normal distribution.
- Mean: Mean is whereas average of the data.
- Standard_Dev: Standard Deviation is a function to find the deviation of the data. (It has to be a positive number)
The graph we plot on this data is called a normal distribution graph. It is also known as a bell curve. What is the bell curve? A bell curve is a common distribution for a variable, i.e. how evenly a data is distributed. It has some. The chart we plot can be a line chart or scatter chart with smoothed lines.
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How to Make a Normal Distribution Graph in Excel?
Below are the examples of normal distribution graphs in excel (Bell Curve)
Normal Distribution Graph Example #1
First, we will take a random data. Let us take values from -3 to 3 in column A. Now we need to calculate mean and standard deviation in excel before calculating the normal distribution and then we can make the excel normal distribution graph.
So, have a look at the data below
- First calculate the Mean of the data i.e. average of the data, in Cell D1 write the following formula.
Press enter to get the result.
- Now we will calculate the standard deviation for the given data, so in the cell, D2 write the following formula.
Press enter to get the result.
- Now in cell B2, we will calculate the normal distribution by the built-in formula for excel. Write down the following formula in cell B2.
- The formula returns the result as shown below:
- Now drag the formula to cell B7.
- In cell B2 we have the normal distribution for the data we have chosen. To make a normal distribution graph go to Insert tab and in Charts select scatter chart with smoothed lines and markers.
- When we insert the chart we can see that our bell curve or normal distribution graph is created.
The above chart is the normal distribution graph for the random data we took. Now we need to understand something first before we move on to a real-life example of data. Standard Deviation S means Standard Deviation Sample because in real data analysis we have a huge chunk of data and we pick a sample of data from that to analyze.
Normal Distribution Graph Example #2
Moving on to a real-life example. The more the data we have the more smooth line we will get for our bell curve or excel normal distribution graph. To prove that I will take an example of employees and their incentives achieved for the current month. Let us take an example for 25 employees.
Consider the below data.
- Now the first step is to calculate the mean which is the average for the data in excel. Type the following formula for a mean.
The Mean of the data is 13,000.
- Now let us find the standard deviation for the data. Type the following formula.
Standard Deviation for the data is 7359.801.
- As we have calculated both mean and the standard deviation now we can go ahead and calculate the normal distribution for the data. Type the following formula.
- Normal distribution Function returns the result as shown below:
- Drag the formula to cell B26.
- Now as we have calculated our normal distribution we can go ahead and create the bell curve of normal distribution graph of the data. In the Insert tab under the charts, section click on scatter chart with smoothed lines and markers.
- When we click ok we see the following chart created,
We took 25 employees as the sample data we can see that in the horizontal axis the curve stops at 25.
The above chart was the normal distribution graph or bell curve for the data for employees and the incentives they achieved for the current month.
Excel Normal Distribution is basically a data analysis process that requires few functions such as mean and standard deviation of the data. The graph made on the normal distribution achieved is known as the normal distribution graph or the bell curve.
Things to Remember About Normal Distribution Graph in Excel
- Mean is the average of data.
- Standard Deviation should be positive.
- The horizontal axis represents the sample count we picked for our data.
- Normal Distribution is also known as the bell curve in Excel.
This has been a guide to the Normal Distribution Graph in Excel. Here we look at how to create a Normal Distribution Graph in Excel with a downloadable excel template. You may learn more about excel from the following articles –