Rank Bias

Syntax: choose Parametric field from drop down list

Selects a numeric Parametric field to add to each document's rank at search time. This can be used to bias results up or down in relevance-ranked searches, based on arbitrary criteria (e.g. file type, importance, etc.) on a document-by-document basis. The chosen field can be overridden at search time with the rankBias query parameter (here); the rules below apply regardless of how the field is chosen.

The Rank Bias field must be set Sortable under Parametric Search Options, as it will be used during sorting. It must also be an Integer or Numeric type. For best results, the field should also be listed in Compound Index Fields (here).

Each document's value for the Rank Bias field may be positive, negative, or zero, to either increase, decrease, or not change the rank by the given percentage. E.g. a Rank Bias field value of 3 will increase the rank for that document by 3%. It is possible to increase the final rank to over 100% (or under 0%); this can be trimmed to the 0-100% range at display time if desired by using the XSL Stylesheet value for Results Style (here) and editing the XSL appropriately.

The Data from Field settings (here) are used to populate the Rank Bias field for each document, according to desired policy (file type, meta data, etc.). See here for an example.

Note that while Rank Bias cannot be applied to a meta-search profile, it can be applied to a meta-search's target profiles - if the targets are Parametric. See also the Bias setting (here) for meta search (target-)profile-wide biasing.