Difference between excel skew and calculated skew
Hi I have calculated skewness for a couple of data sets and find there is a discrepancy between my calculated skewness (sample) and that calculated using the excel sample skewness function skew().
In this exercise: Descriptive Statistics Fundamentals: Assignment: Skewness, Task 1
I calculated a skew of 0.569 and excel calculates 0.631
What is the cause of this difference? For reference I used the formula found at the start of the respective video lesson.
I found solution!
That problem occurs because Excel use an another type of formula:
Excel offers the following built-in function to calculate the skewness of a distribution: =SKEW(array of values)
This function uses the following formula to calculate skewness:
Skewness = [n/(n-1)(n-2)] * Σ[(xi–x)/s]3
n = sample size
Σ = fancy symbol that means “sum”
xi= the value of the ith value in the dataset
x = mean
s = standard deviation