## Package

**weka.filters.unsupervised.attribute**

## Synopsis

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

Outliers:

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

or

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

Extreme values:

x > Q3 + EVF*IQR

or

x < Q1 - EVF*IQR

Key:

Q1 = 25% quartile

Q3 = 75% quartile

IQR = Interquartile Range, difference between Q1 and Q3

OF = Outlier Factor

EVF = Extreme Value Factor

## Options

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 |

## Capabilities

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 |