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A filter for detecting outliers and extreme values based on interquartile ranges. The filter skips the class attribute.

Q3 + OF*IQR < x <= Q3 + EVF*IQR
Q1 - EVF*IQR <= x < Q1 - OF*IQR

Extreme values:
x > Q3 + EVF*IQR
x < Q1 - EVF*IQR

Q1 = 25% quartile
Q3 = 75% quartile
IQR = Interquartile Range, difference between Q1 and Q3
OF = Outlier Factor
EVF = Extreme Value Factor


The table below describes the options available for InterquartileRange.

Option Description
attributeIndices Specify range of attributes to act on; this is a comma separated list of attribute indices, with "first" and "last" valid values; specify an inclusive range with "-", eg: "first-3,5,6-10,last".
debug Turns on output of debugging information.
detectionPerAttribute Generates Outlier/ExtremeValue attribute pair for each numeric attribute, not just a single pair for all numeric attributes together.
extremeValuesAsOutliers Whether to tag extreme values also as outliers.
extremeValuesFactor The factor for determining the thresholds for extreme values.
outlierFactor The factor for determining the thresholds for outliers.
outputOffsetMultiplier Generates an additional attribute 'Offset' that contains the multiplier the value is off the median: value = median + 'multiplier' * IQR


The table below describes the capabilites of InterquartileRange.

Capability Supported
Class Unary class, Relational class, Date class, Missing class values, Numeric class, No class, String class, Empty nominal class, Binary class, Nominal class
Attributes Missing values, Nominal attributes, String attributes, Empty nominal attributes, Relational attributes, Binary attributes, Date attributes, Unary attributes, Numeric attributes
Min # of instances 0

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