What is Standard Deviation?

Standard deviation is a statistical measure that quantifies the amount of variation or dispersion in a set of values. In simpler terms, it tells you how much your data "spreads out" from the average (mean). A low standard deviation indicates that the data points tend to be close to the mean, while a high standard deviation indicates that the data points are spread out over a wider range of values.

How to Calculate Standard Deviation in Excel

Calculating standard deviation in Excel is straightforward because the software includes built-in functions to handle the complex math for you. Depending on your data set, you will use one of two primary formulas:

1. STDEV.S (Sample Standard Deviation): Use this formula when your data is a sample of a larger population. For example, if you are analyzing the heights of 50 students to estimate the height of the entire university.
Formula: =STDEV.S(A1:A50)

2. STDEV.P (Population Standard Deviation): Use this formula when you have the data for the entire group you are studying. For example, if you have the test scores for every single student in a specific classroom.
Formula: =STDEV.P(A1:A50)

Step-by-Step Guide

Follow these steps to get your results in seconds:

• Open your Excel spreadsheet and select the cell where you want the result to appear.
• Type =STDEV.S( or =STDEV.P(.
• Highlight the range of cells containing your numbers (e.g., B2 to B20).
• Close the parenthesis ) and press Enter.

Frequently Asked Questions

What is the difference between STDEV and STDEV.S?
In older versions of Excel, STDEV was the default. In newer versions, STDEV.S replaced it to clarify that it calculates the sample standard deviation. They provide the same result.

Can I calculate standard deviation for non-numeric data?
No, standard deviation requires numerical values. If your range includes text or empty cells, Excel functions like STDEV.S will typically ignore them, but it is best to clean your data first.