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Table of Contents Statistical Tests Outlier Tests Walsh's Outlier Test | |
See also: Outlier Test - Dean and Dixon |
Let X_{1}, X_{2}, ... , X_{n} represent the data ordered from smallest to largest. If n<60, do not apply this test. If 60<n<=220, then a = 0.10. If n >220 then a = 0.05.
Step 1: | Identify the number of possible outliers, r >= 1. |
Step 2: | Compute where ceil() indicates rounding the value to the largest possible integer (i.e., 3.21 becomes 4). |
Step 3: | The r smallest points are outliers (with a a% level of significance) if X_{r} - (1+a)X_{r+1} + aX_{k} < 0 |
Step 4: | The r largest points are outliers (with a a% level of significance) if X_{n+1-r} - (1+a)X_{n-r} + aX_{n+1-k} > 0 |
Step 5: | If both of the inequalities are true, then both small and large outliers are indicated. |
Last Update: 2005-Mai-08