How to Calculate Standard Deviation in Excel
Calculating the standard deviation in Excel may seem daunting at first, especially for those who are new to using spreadsheets. However, Excel makes it relatively easy to track the spread of your data for better analysis by providing a built-in formula for standard deviation.
Before we dive into the steps, let’s first review what standard deviation is. It is a statistic that measures the amount of variation or dispersion within a set of data. In other words, it shows how much the data deviates from the average or mean value. So, if the standard deviation is high, the data is more spread out, and if the standard deviation is low, the data is closer to the mean.
Now, let’s see how you can calculate the standard deviation in Excel.
Step 1: Enter Your Data
Enter your data values into a column or row within your Excel worksheet.
Step 2: Calculate the Mean
Calculate the arithmetic mean (average) of your data set by using the “AVERAGE” formula. Simply select the cell where you want the result to appear and then type =AVERAGE(range), where “range” is the range of cells where your data is stored.
Step 3: Calculate Deviations
Calculate the deviations from the mean. To do this, you’ll need to subtract each data point from the mean value you just calculated. You can create a column (or row) next to your data with the header “Deviations” and then use the “=A2-mean” formula for each data point. Here, ‘A2’ is the cell location where the first data point is stored.
Step 4: Square Each Deviation
To avoid the problem of negative values, square each deviation result using the “=POWER(x,2)” formula. This will ensure that your calculations will not ignore the impact of negative values in the data. You can do this by creating another column or row with the header “Deviation Squared,” and then use the “=POWER(B2,2)” formula for each deviation value.
Step 5: Calculate the Variance
Next, calculate the variance by taking the sum of the squared deviations and dividing it by the number of data points, using the “=SUM(range)/(count-1)” formula. Here, “range” is the range of cells where your squared deviations are stored, and “count” is the number of data points in your set. Note that we are using count-1 because we are calculating what is known as a “sample” variance, and not a “population” variance. If you have the entire population data, you should use just ‘count’ instead of ‘count-1’ in the formula.
Step 6: Calculate the Standard Deviation
Finally, calculate the standard deviation by taking the square root of the variance. Use the “=SQRT(variance)” formula which means taking the square root of the cell where you have stored the variance.