How to Use the SKEW and SKEW.P Functions in Excel

By Stephen L. Nelson, E. C. Nelson

Excel offers you the use of SKEW and SKEW.P functions. These statistical functions can be enormously helpful when dealing with normal distributions. The SKEW and SKEW.P functions measure the symmetry of a distribution of values. Both functions use the same syntax, so only the SKEW.P function is described here.

The SKEW.P function uses the syntax

=SKEW.P(number1,[number2])

To illustrate this function, suppose that you want to measure the skewness of a perfectly symmetrical distribution, such as the uniformly distributed values 1, 2, 3, 4, 5, 6, 7 and 8. No skewness exists here, right? You can prove this lack of skewness using the formula

=SKEW.P(1,2,3,4,5,6,7,8)

Which returns the value 0.

If a distribution’s values tail (that is, stretch out) to the right, it means the distribution includes greater numbers of large values (or larger values) than a symmetrical distribution would. Thus the skewness is positive. For example, the formula

=SKEW.P(1,2,3,4,5,6,8,8)

returns the value 0.07925.

If the distribution’s values tail (stretch out) to the left, meaning that the distribution includes greater numbers of small values or smaller values than a symmetrical observation would, the skewness is negative. For example, the formula

=SKEW(1,1,3,4,5,6,7,8)

returns the value -0.07924.