The Variance is a statistical measure, that is commonly used across a set of values, to identify the amount that the values vary from the average value.
For any set of values, x, the equation for calculating the Variance is :
where x is the average (statistical mean) of the set of values, and n is the number of values in the set.Further details are provided on the Wikipedia Variance page
The Excel VAR.P function returns the Variance of a given set of values.
The VAR.P function is new to Excel 2010. However, this is simply an improved (slightly more accurate) version of the VARP function, which is available in earlier versions of Excel.
The format of the function is :
Where the number arguments provide a minimum of 2 numerical values to the function. The maximum number of arguments that can be supplied to the VAR.P function is 254.
Note that the Var.P function is used when calculating the variance of an entire population. If your data is just a sample of the population (eg. if your data set records the individual heights of a sample of UK males), you need to use the Var.S function.
Note also, that the Var.P function ignores text values and logical values if these are supplied as part of an array. However, if they are supplied directly to the function, text representations of numbers and logical values are interpreted as numbers. If you want a population variance function that does not ignore text and logical values that are supplied as a part of an array, consider using the Varpa function.
A company keeps a record of its monthly sales figures, over the last three years. These are stored in cells B3 - B14, D3 - D14 and F3 - F14 of the example spreadsheet on the right.
The variance of the three years' sales figures is calculated in cell H3 of the spreadsheet. The formula for this, as shown in the formula bar, is :
As shown in cell H3, the variance for the 3 years of sales figures is 6,170,524.69.
The example above shows the arguments to the Var.P function being input in the form of 3 cell ranges. However, you can also input figures directly, as individual numbers or number arrays.
For example, if, during January and February 2010 the sales figures are 13,000 and 14,500 we can add these directly into the above function as follows:
This gives the updated variance of 5,930,921.05.
Further information and examples of the Excel Var.P function can be found on the Microsoft Office website.
If you get an error from the Excel Var.P Function, this is likely to be the #DIV/0! error:
|#DIV/0!||-||Occurs if fewer than 2 numerical values have been supplied to the function|
Some users may also encounter the following problem with the Var.P function:
If you are getting an unexpected result from the Var.P function, this may be because you are supplying the function with text representations of numbers, rather than numerical values.
The Var.P function will interpret logical values or text representations of numbers if they are supplied directly to the function. However, if the function is supplied with an array of cells containing logical values or text representations of numbers, these cells are ignored in the calculation.
The different Excel data types are explained in more detail on the Excel Formatting page.
You can fix this problem by converting all text representations of numbers into numerical values. One way to do this is using the Text-To-Columns command: