Results > Manipulate Result Relevance > Use the BIAS Field Specifier to Boost Relevance > BIASDATE

BIASDATE
The BIASDATE field operator works in a similar way to the BIAS field operator. It allows you to bias the score of results at query time according to the proximity of the specified field to a given date.
Specify BIASDATE using the format:
BIASDATE{optimumDate,range,percentage}
where,
 
is the date that the field must contain to increase or decrease the result weight by the maximum percentage. See Table 3 for a list of the available date formats.
is a positive value that determines the range in seconds of the specified optimum. If the specified field contains a value that is in the range of (optimumrange) to (optimum + range), the result weight is increased or decreased according to the specified percentage.
is a percentage in the range –100 to 100. If the value of the specified field is within the specified range, the score of the result increases or decreases according to how close the value is to the specified optimum. When Absweight is set to true, this is the absolute value by which to boost the weight and it is then not limited by +/– 100.
For example:
*
A document whose DATE field value is within a range of 10 days (864000 seconds) either side of 1/12/2008 has its weight increased on a linear scale from 10 percent if the date is 1/12/2008, to zero percent if the date is 20/11/2008 or 11/12/2008.
*
A document whose DATE field value is within a range of 10 days (864000 seconds) either side of 1/12/2008 has its weight decreased on a linear scale from –10 percent if the date is 1/12/2008, to zero percent if the date is 20/11/2008 or 11/12/2008.