for the following 3 values 222,1122,45444
WolframAlpha gives 0.706
=SKEW(222,1122,45444) gives 1.729
What explains the difference?
They are using different methods to compute the skew. Searching in the help pages for
skewness() within the R package
Joanes and Gill (1998) discuss three methods for estimating skewness: Type 1: g_1 = m_3 / m_2^(3/2). This is the typical definition used in many older textbooks. Type 2: G_1 = g_1 * sqrt(n(n-1)) / (n-2). Used in SAS and SPSS. Type 3: b_1 = m_3 / s^3 = g_1 ((n-1)/n)^(3/2). Used in MINITAB and BMDP. All three skewness measures are unbiased under normality. #Why are these numbers different? > skewness(c(222,1122,45444), type = 2)  1.729690 > skewness(c(222,1122,45444), type = 1)  0.7061429
Here's a link to the paper referenced if someone has the credentials to get it for further discussion or education: http://onlinelibrary.wiley.com/doi/10.1111/1467-9884.00122/abstract