How to Use DSTDEVP Function in Google Sheets

The DSTDEVP function in Google Sheets is useful if you need to calculate the standard deviation of a population based on the entire population by using the numbers in a field (column) of records in a list or database that match conditions that you specify.

The DSTDEVP function is a built-in function that is categorized as a ‘Database Function’. It can be used as a worksheet function, and can be entered as part of a formula in a cell of a worksheet.

What is a standard deviation?

For given data, the standard deviation is a measure of dispersion in statistics. “Dispersion” tells you how much your data is spread out. It demonstrates how much your data is spread out around the meaning or average. For example, are all your scores close to the average? Or are lots of scores way above (or way below) the average score.

Let’s take an example.

A class of students took a mathematics test. Their tutor wants to validate whether most students are performing at the same level, or if there is a high standard deviation. By calculating the mean score, the tutor gets a high score. But is everyone performing at that level? 

Here is where the DSTDEVP() function comes to her aid. The function outputs the standard deviation of the set of marks for all students, which is the population set in this case. The standard deviation of these tests is around 6.2 points out of 100. Since the value is somewhat low, the tutor knows that most students are performing around the same level.

That’s just one example. There are plenty of other use-cases for this function in real life. Great! Let’s dive right into such real-business use-cases, where we will deal with actual values and as well as learn how we can write our own DSTDEVP() function in Google Sheets to calculate variances in data.

 

 

The Anatomy of the DSTDEVP Function

So the syntax (the way we write) of the DSTDEVP() function is as follows:

=DSTDEVP(database, field, criteria)

Let’s dissect this thing and understand what each of the terms means:

  • = the equal sign is just how we start any function in Google Sheets.
  • DSTDEVP() is our DSTDEVP function. DSTDEVP will return the variance of an entire population selected from a database table-like array or range using a SQL-like query.
  • database refers to the array or range having the data, including headers for each column’s values
  • field refers to the column in the data which has the values that are to be extracted and worked on.
    • field may either be a text label referring to the required column header or a numeric value indicating which column to consider, where the first column has a value = 1.
  • criteria refers to an array or range containing the criteria to filter the database values before operating. This may be left blank.

For better understanding of the difference between estimating variance from a population vs. a sample, we shall be explaining the function using the same examples from our guide on DSTDEVP() function, so that you can compare the two.

 

 

A Real Example of Using DSTDEVP Function

Take a look at the example below to see how DSTDEVP() functions are used in Google Sheets.

DSTDEVP in Google Sheets

 

The above are the only five purchases Linda made at the grocery store this week. As is evident from the quantities purchased, she went a bit overboard with the third purchase. She wanted to know if her high-priced purchases were in the same price range as her low-priced purchases..

Just above the captured data, I have given a provision to enter the criteria based on which the data will be filtered. This is not a required criterion, and the function will still function properly if we leave it blank.

The DSTDEVP() function will give her the desired result based on the conditions specified in A2:D3, as below:

DSTDEVP example

 

What does the 0.5 value mean here? The two orders which have a unit cost of more than $3 are Order IDs 1 and 5, costing $5 and $6 respectively. The function gives a standard deviation of 0.5, which means the values ($5 and $6) are not too different from the mean value ($5.5).

You may try changing the criteria and see how the result changes. Go ahead and make a copy of the spreadsheet using the link I have attached below:

Awesome! Let’s begin our DSTDEVP() function in Google Sheets.

 

 

How to Use DSTDEVP Function in Google Sheets

  1. Let’s see how to write your own DSTDEVP() function, step-by-step. First of all, I have pasted sales data from a single retail store across three years, from 2018 to 2020, for three apparel brands – Nike, Adidas, and Puma.

Sales table

 

  1. Now, simply click on any cell to make it the active cell. For this guide, I will be selecting F14, where I want to show my results.
  2. Next, simply type the equal sign ‘=‘ to begin the function and then followed by the name of the function, which is our ‘dstdevp‘ (or DSTDEVP, whichever works).
  3. You should find that the auto-suggest box appears with our function of interest. Continue by entering the first opening bracket ‘(‘. If you get a huge box with text in it, simply hit the arrow in the top-right hand corner of the box to minimize it. You should now see it as follows:

DSTDEVP in Google Sheets

 

  1. Now, the fun begins! Let’s give the required inputs to the function to get the standard deviation in unit sales, per the filtration criteria we have given above the data:

DSTDEVP in Google Sheets

 

  1. Take note of how I’ve specified conditions to limit the data to the Nike brand (selecting only the years 2019 and 2020). The criteria for the formula are input as A1:F3 to account for all the criteria mentioned, if any.
  2. Once you’ve entered the necessary database, field, and criterion values, or you’ve done what I did, make sure to close the brackets ‘)’, as shown below.

DSTDEVP sample walkthrough

 

  1. Finally, just hit your Enter key. If you followed my instructions, you should have gotten 273.86 as the function’s output, which is nothing but the standard deviation of Nike and Puma combined unit sales (for the criteria specified above the data table).

DSTDEVP sample walkthrough output

 

As per the specified criteria, the sales units that qualify to be considered vary from 800 units to 1,500 units with an average value of 1,100 units. The standard deviation obtained denotes that the data points aren’t that close to each other.

That’s pretty much it. You have everything you need to get started with the DSTDEVP() function on Google Sheets. I recommend experimenting with the DSTDEVP() function, combining it with the numerous Google Sheets formulas available, and seeing what you can come up with. 🙂

 

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