# Excel STDEV.P vs STDEV.S: Dive into Variance Analysis

Written by Kasper Langmann

Understanding the intricacies of statistical analysis can be a daunting task. However, tools like Microsoft Excel provide us with powerful functions that simplify these complex calculations. Two such functions are STDEV.P and STDEV.S, which are used to calculate standard deviation, a key measure in variance analysis. This article will delve into the details of these two functions, their differences, and their applications in statistical analysis.

## Understanding Standard Deviation

Before we delve into the specifics of STDEV.P and STDEV.S, it’s important to understand what standard deviation is. In statistics, standard deviation is a measure that quantifies the amount of variation or dispersion in a set of values. A low standard deviation indicates that the values tend to be close to the mean (or expected value), while a high standard deviation indicates that the values are spread out over a wider range.

Standard deviation is a crucial concept in fields such as finance, quality control, and any other field that relies on statistical analysis. It helps analysts understand the volatility, risk, or quality variation in their data sets. In Excel, standard deviation can be calculated using various functions, including STDEV.P and STDEV.S.

## Excel STDEV.P Function

The STDEV.P function in Excel calculates the standard deviation based on the entire population given as arguments. In statistical terms, ‘population’ refers to the complete set of data from which a statistical sample is drawn. The ‘P’ in STDEV.P stands for ‘Population’.

This function uses the following syntax: STDEV.P(number1, [number2], …). The arguments can be numbers, arrays, or references that contain numbers. If an argument is an array or reference, only numbers in that array or reference are used. Empty cells, logical values, or text in the array or reference are ignored.

### When to Use STDEV.P

STDEV.P should be used when your data represents the entire population. For example, if you’re analyzing the average height of all the students in a school, the data set would represent the entire population, and thus, STDEV.P would be the appropriate function to use.

It’s also worth noting that STDEV.P assumes that its arguments are the entire population. If your data is a sample of the population, then the standard deviation calculated by STDEV.P can underestimate the population standard deviation.

## Excel STDEV.S Function

The STDEV.S function, on the other hand, calculates the standard deviation based on a sample of the population. The ‘S’ in STDEV.S stands for ‘Sample’. This function uses the following syntax: STDEV.S(number1, [number2], …).

Just like STDEV.P, the arguments can be numbers, arrays, or references that contain numbers. Non-numeric values in the array or reference are ignored.

### When to Use STDEV.S

STDEV.S should be used when your data is a sample of the entire population. For instance, if you’re analyzing the average height of a group of students from a school, the data set would represent a sample of the population, and thus, STDEV.S would be the appropriate function to use.

It’s important to note that STDEV.S assumes that its arguments are a sample of the population. If your data represents the entire population, then the standard deviation calculated by STDEV.S can overestimate the population standard deviation.

## Differences Between STDEV.P and STDEV.S

While STDEV.P and STDEV.S are used for the same purpose – to calculate standard deviation – the key difference lies in whether they consider the data set to be a sample of the population or the entire population. This difference can significantly impact the result of the standard deviation calculation.

Another difference is in the way these two functions calculate standard deviation. STDEV.P uses the ‘n’ method, which divides by the number of data points when calculating the standard deviation. On the other hand, STDEV.S uses the ‘n-1’ method, which divides by the number of data points minus one.

## Conclusion

Understanding the difference between STDEV.P and STDEV.S is crucial for accurate statistical analysis in Excel. By knowing when to use each function, you can ensure that your standard deviation calculations accurately reflect the data set you’re working with.

Remember, if your data set represents the entire population, use STDEV.P. If it’s a sample of the population, use STDEV.S. By doing so, you’ll be on your way to mastering variance analysis in Excel.