How to use the DSTDEVP function

What is the DSTDEVP function?

The DSTDEVP function calculates the standard deviation based on a population. The function also allows you to specify criteria applied to your data.

1. Introduction

What is DSTDEVP an abbreviation of?

DSTDEVP is an abbreviation of database standard deviation population.

What is Standard Deviation?

Standard deviation tells you how far from the average values are spread out. Both charts above have numbers and an average plotted, they share the exact same average however, the numbers are not the same.

Chart A above shows that the values are more spread out than the values in chart B. Chart A has a standard deviation of 23.45256334, standard deviation for chart B is 5.207075606. Standard deviation is fundamental in statistics.

A normal distribution is a symmetric, bell-shaped probability distribution that is commonly used in statistics and probability theory. The shape of the normal distribution is determined by its mean (μ) and standard deviation (σ). The mean represents the center of the distribution, while the standard deviation represents the spread or dispersion of the data around the mean.

• A normal distribution with a standard deviation of 0.5 is relatively narrow and tightly clustered around the mean.
  
  The values in the distribution are concentrated within a smaller range, with most values falling closer to the mean. The curve appears tall and steep, indicating a higher concentration of data points near the mean.
• A normal distribution with a standard deviation of 1 is the most commonly used normal distribution, often referred to as the standard normal distribution.
  
  The standard deviation of 1 represents a moderate spread of the data around the mean. About 68% of the data falls within one standard deviation (±1σ) of the mean, and approximately 95% of the data falls within two standard deviations (±2σ) of the mean. The curve has a characteristic bell shape, with a smooth and gradual taper towards the tails.
• A normal distribution with a standard deviation of 2 is relatively wide and spread out compared to the standard normal distribution. The data is dispersed over a larger range, with values more spread out from the mean. The curve appears shorter and flatter, indicating a lower concentration of data points near the mean.

Does the DSTDEVP function count blank cells, boolean, and text values?

No, blank cells, boolean values and text values are not counted.

Does the DSTDEVP function ignore error values?

No, it doesn't. However, error values are ignored if they are filtered out by the criteria argument.

What is a database in this context?

Excel defines a database as a list of related data in which rows of related information are records, and columns of data are fields. The first row of the list contains labels for each column.

Why use the DSTDEVP function?

The DSTDEVP function calculates the standard deviation of cells containing numbers that match a condition or criteria in a list/database whereas the STDEVP function calculates the standard deviation without a condition/criteria.

Where can you place the criteria range?

You can place your criteria range wherever you want on your worksheet, however, it is not recommended below the list/database. The function needs a blank row below the list to work properly.

What criteria characters are allowed?

Allowed criteria range characters are less than and greater than signs <>, use them to specify a criteria range. Also, asterisks * can be used to match partial strings.

How to calculate the standard deviation for the entire list/database?

To include the entire list/database enter a blank line below the criteria range column labels.

2. Syntax

DSTDEVP(database, field, criteria)

database	Required.  The cell reference to a list or database.
field	Required. The field argument lets you choose which column to use. You can use the column name enclosed with double quotation marks or the corresponding column number.
criteria	Required.  A cell reference to the criteria range. The criteria range needs to have column labels and at least one condition below the column label.

3. Example 1

You have a dataset containing the widths of a product manufactured by a company. Calculate the population standard deviation of the width values to understand the spread of the manufactured products? There are three categories, Large, Small and Medium. Find the standard deviation of products in category "Large".

The data is in cell range B15:D16 in the image above, here are they:

Item	Size	Number
A102	M	370
A103	L	690
A099	S	310
A412	S	190
A341	L	550
A340	M	730
A202	L	623

The arguments are:

• database = B18:D25
• field = 3 (third column)
• criteria = B15:C16

Formula in cell B28:

The formula returns 57.17 which represents the standard deviation based on a population. The math formula behind is:

DSTDEVP function = √(Σ(x - x̄)²/n)

√ - square root
Σ - sum of
x̄ - arithmetic mean
n - count of values

The values that match the condition "L" in cell range B18:D25 are 690, 550, and 623. The mean is 690 + 550 + 623 equals 1863. 1863 / 3 equals 621.

690 - 621 = 69
550 - 621 = -71
623 - 621 = 2

The square of these values are:
69² = 4761
(-71)² = 5041
2² = 4

The total is 4761 + 5041 + 4 = 9806
9806/3 = 3268.6666667
√3268.6666667 = 57.17 which is the same value in cell B28.

4. Example 2

A researcher studying a company has compiled data on the lifespan of a certain machine. Assume the data follows a normal distribution. Calculate the standard deviation from numbers in D19:D25, based on "Items" in B19:B25 that begin with "A"?

The data is in cell range B15:D16 in the image above, here are they:

Item	Size	Number
B102	M	370
A103	L	690
B099	S	310
A412	S	190
A341	L	550
B340	M	730
A202	L	623

The arguments are:

• database = B18:D25
• field = 3 (third column)
• criteria = B15:C16

Cell B16 contains "A*" meaning that all values that begins with A are valid. The asterisk matches 0 (zero) to any number of characters.

Formula in cell B28:

The formula returns 193.08 which represents the standard deviation based on a population. The math formula behind is:

DSTDEVP function = √(Σ(x - x̄)²/n)

√ - square root
Σ - sum of
x̄ - arithmetic mean
n - count of values

The values that match the condition "A*" in cell range B18:D25 are 690, 190, 550, and 623. The mean is 690 + 190 + 550 + 623 equals 2053. 2053 / 4 equals 513.25

690 - 513.25 = 176.75
190 - 513.25 = -323.25
550 - 513.25 = 36.75
623 - 513.25 = 109.75

The square of these values are:
176.75² = 31240.5625
(-323.25)² = 104490.5625
36.75² = 1350.5625
109.75² = 12045.0625

The total is 31240.5625 + 104490.5625 + 1350.5625 + 12045.0625 = 149126.75
149126.75/4 = 37,281.6875
√37,281.6875 = 193.08 which is the same value in cell B28.

5. Function not working

The DSTDEVP function

• returns a #VALUE! error if the field argument is out of range.
• propagates errors in the source data.

5.1 Troubleshooting the error value

When you encounter an error value in a cell a warning symbol appears, displayed in the image above. Press with mouse on it to see a pop-up menu that lets you get more information about the error.

1. The first line describes the error if you press with left mouse button on it.
2. The second line opens a pane that explains the error in greater detail.
3. The third line takes you to the "Evaluate Formula" tool, a dialog box appears allowing you to examine the formula in greater detail.
4. This line lets you ignore the error value meaning the warning icon disappears, however, the error is still in the cell.
5. The fifth line lets you edit the formula in the Formula bar.
6. The sixth line opens the Excel settings so you can adjust the Error Checking Options.

Here are a few of the most common Excel errors you may encounter.

#NULL error - This error occurs most often if you by mistake use a space character in a formula where it shouldn't be. Excel interprets a space character as an intersection operator. If the ranges don't intersect an #NULL error is returned. The #NULL! error occurs when a formula attempts to calculate the intersection of two ranges that do not actually intersect. This can happen when the wrong range operator is used in the formula, or when the intersection operator (represented by a space character) is used between two ranges that do not overlap. To fix this error double check that the ranges referenced in the formula that use the intersection operator actually have cells in common.

#SPILL error - The #SPILL! error occurs only in version Excel 365 and is caused by a dynamic array being to large, meaning there are cells below and/or to the right that are not empty. This prevents the dynamic array formula expanding into new empty cells.

#DIV/0 error - This error happens if you try to divide a number by 0 (zero) or a value that equates to zero which is not possible mathematically.

#VALUE error - The #VALUE error occurs when a formula has a value that is of the wrong data type. Such as text where a number is expected or when dates are evaluated as text.

#REF error - The #REF error happens when a cell reference is invalid. This can happen if a cell is deleted that is referenced by a formula.

#NAME error - The #NAME error happens if you misspelled a function or a named range.

#NUM error - The #NUM error shows up when you try to use invalid numeric values in formulas, like square root of a negative number.

#N/A error - The #N/A error happens when a value is not available for a formula or found in a given cell range, for example in the VLOOKUP or MATCH functions.

#GETTING_DATA error - The #GETTING_DATA error shows while external sources are loading, this can indicate a delay in fetching the data or that the external source is unavailable right now.

5.2 The formula returns an unexpected value

To understand why a formula returns an unexpected value we need to examine the calculations steps in detail. Luckily, Excel has a tool that is really handy in these situations. Here is how to troubleshoot a formula:

1. Select the cell containing the formula you want to examine in detail.
2. Go to tab “Formulas” on the ribbon.
3. Press with left mouse button on "Evaluate Formula" button. A dialog box appears.
   The formula appears in a white field inside the dialog box. Underlined expressions are calculations being processed in the next step. The italicized expression is the most recent result. The buttons at the bottom of the dialog box allows you to evaluate the formula in smaller calculations which you control.
4. Press with left mouse button on the "Evaluate" button located at the bottom of the dialog box to process the underlined expression.
5. Repeat pressing the "Evaluate" button until you have seen all calculations step by step. This allows you to examine the formula in greater detail and hopefully find the culprit.
6. Press "Close" button to dismiss the dialog box.

There is also another way to debug formulas using the function key F9. F9 is especially useful if you have a feeling that a specific part of the formula is the issue, this makes it faster than the "Evaluate Formula" tool since you don't need to go through all calculations to find the issue..

1. Enter Edit mode: Double-press with left mouse button on the cell or press F2 to enter Edit mode for the formula.
2. Select part of the formula: Highlight the specific part of the formula you want to evaluate. You can select and evaluate any part of the formula that could work as a standalone formula.
3. Press F9: This will calculate and display the result of just that selected portion.
4. Evaluate step-by-step: You can select and evaluate different parts of the formula to see intermediate results.
5. Check for errors: This allows you to pinpoint which part of a complex formula may be causing an error.

The image above shows cell reference B18:D25 converted to hard-coded value using the F9 key. The DSTDEVP function requires non-error values which is not the case in this example. We have found what is wrong with the formula.

Tips!

• View actual values: Selecting a cell reference and pressing F9 will show the actual values in those cells.
• Exit safely: Press Esc to exit Edit mode without changing the formula. Don't press Enter, as that would replace the formula part with the calculated value.
• Full recalculation: Pressing F9 outside of Edit mode will recalculate all formulas in the workbook.

Remember to be careful not to accidentally overwrite parts of your formula when using F9. Always exit with Esc rather than Enter to preserve the original formula. However, if you make a mistake overwriting the formula it is not the end of the world. You can “undo” the action by pressing keyboard shortcut keys CTRL + z or pressing the “Undo” button

5.3 Other errors

Floating-point arithmetic may give inaccurate results in Excel - Article

Floating-point errors are usually very small, often beyond the 15th decimal place, and in most cases don't affect calculations significantly.

Functions in 'Database' category

The DSTDEVP function function is one of 11 functions in the 'Database' category.

Excel function categories

Excel categories

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