Standard Deviation Outlier Treatment

For this treatment, an outlier is an attribute with a value that is some number of Multiples of Sigma (the standard deviation) from the mean; the default number of Multiples of Sigma is 3. If AVG is the mean of the attribute and s is the standard deviation, then attributes with values less than M-3s or greater than M+3s are outliers.

You must also specify what value to replace outliers with. You can either replace outliers values with nulls (that is, "throw the values away") or you can replace them with edge values. In the example above, the edge values are M-3s and M+3s. If you specify Replace with edge values and if the value of an attribute is greater than M+3s, that value is replaced with M+3s; values less than M-3s are replaced with M-3s. The default is to Replace with nulls.

When you are done defining the treatment, click OK.