Excel Standard Deviation Formula (Table of Contents)
Standard Deviation Formula in Excel
Standard Deviation is widely used in statistical calculation. Standard Deviation is the deviation of range about the mean value. Or if we say in simple words, it shows how much the number or values are differing from mean value of selected range.
There are two types of Standard Deviations;
- Low Standard Deviation
- High Standard Deviation
Low Standard Deviation has a value of standard deviation close to mean value by this the curve becomes more stiff at the top and small towards the bottom. Where as in High Standard Deviation, standard deviation has value away from mean value with this curve becomes smooth at the top and wider towards the bottom.
How to Use Standard Deviation Formula in Excel?
Let’s understand how to calculate Standard Deviation in Excel using formula using some examples and how to plot a graph of Standard Deviation in Excel.
Syntax for Standard Deviation Formula in Excel –
Standard Deviation formula can be used from Insert Function which is situated beside the formula bar by clicking on the fx icon.
Standard Deviation Formula in Excel – Example #1
We have sample sales data of a product, where we observed the huge deviation in the sale for 10 days. So, now let’s see and calculate how much deviation we are getting for the selected data set.
For calculating standard deviation first, go to the cell where we need the output. Then go to insert function option located besides formula bar as shown below.
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Once we do that, we will get the Insert Function box. Now from here select Standard Deviation function which is available as STDEV from Statistical category from the Or select a category or from there select ALL category to look for required function as shown below. Once we are done with selecting the function, click on OK.
Once we click on OK, it will take us to Function Argument of Standard Deviation. Now we will see two number ranges, Number1 and Number2. Go to Number1 and select the complete range. Here we have selected range from cell B2 to B10.
Note – Any number range can accommodate only 255 cell count. If it exceeds, we can use Number2, Number3… as so on.
As we can see in the above screenshot, for the selected range we already have formula result at the bottom left of the box. If the selected range is incorrect then there will not be any value shown.
After clicking on OK, we can see the standard deviation of the selected range in the selected cell.
Now let’s understand, what it means. As we can see our standard deviation value is showing as 23.16127, which means for the selected range if our mean comes as 31.22 then selected range can deviate 23.16127 about the mean value.
Standard Deviation Formula in Excel – Example #2
There is another way to calculate Standard Deviation formula in Excel. For that let’s consider the same data which we have seen in the above example.
For calculating standard deviation formula in excel, go to the cell where we want to see the result and type ‘=’ (Equal) sign. This will enable all the inbuilt functions in excel. Now, search for Standard Deviation by typing STDEV which is the key word to find and select it as shown below.
Now select the complete range. Here we have selected the range from cell B2 to B10.
Press Enter to come out of the edit mode and we will see the calculated value of standard deviation as shown below.
As we can see the standard deviation value is coming as 23.16127. We can also calculate the mean value of the same data, to compare how much deviation of data we are getting about the mean value with the help of AVERAGE formula.
For the demonstration, we have shown how standard deviation and mean are connected with each other. The mean value 31.222 is at the center line of the whole range and Standard Deviation is little far away from the mean value. It can be towards both sides of the mean.
Also, for the value which has decimal digits up to 4 and 5 we can make it in round figure by using ROUND function before the standard deviation. For the type ROUND before STDEV and select the num_digit as 0 as shown below. Once we press Enter, we will get the round figure value of standard deviation as shown below. This will give us the perfect rounded value which we can use further for other analysis.
Standard Deviation Formula in Excel – Example #3
Let’s see another set of data for Standard Deviation calculation in Excel as shown below.
Now as shown in the above example 1 and 2, calculate the Standard Deviation and Mean.
Now for plotting it on a graph, select the complete data and go to Insert Menu, under Charts select Scatter chart with Smooth Lines and Markers which is best suited for plotting Standard Deviation as shown below.
Once we click on it, we will get the points plotted on the graph for Standard Deviation as shown below.
As we can see above, we got a curve and all the points are in the range of it.
Things to Remember About Standard Deviation Formula in Excel
- Select the complete range. If there is any cell break then consider the cell break as well by including that into range.
- Always consider the reference of Mean value so that calculated standard deviation can be measured about.
- Standard Deviation formula in excel always deviates from both side of the mean value but in some cases, it can be skewed towards any of the axis.
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