Use the BIAS Field Specifier to Boost Relevance

The BIAS field specifier allows you to bias the score of results at query time according to the numerical proximity of the specified field to a particular value. It ignores initial dollar ($), pound sign (£), or hyphen (–) characters in the field names.

Specify BIAS in the format:



optimum is the value that the field must contain to increase or decrease the result weight by the maximum percentage.
range is a positive number that determines the range of the optimum. If the specified field contains a value that is in the range of (optimumrange) to (optimum + range), the result weight increases or decreases according to the specified percentage.
percentage is a percentage in the range –100 to 100. If the value of the specified field is in the specified range, the score of the result increases or decreases according to how close the value is to the specified optimum.

For example: