Summary: Result biasing is a method for influencing the order in which results are returned. Biasing can be either on source, date, or metadata.
Cause: Result Biasing does exactly that, it Biases results! The GSA uses internal proprietary algorithms to determine the order in which results are returned. As such the biasing does not sort by default, but rather skews results in favor of the bias setting. If you believe that the bias is having no effect at all please see the below troubleshooting topics
Troubleshooting Steps: To debug the effect biasing is having on results please see the official documentation's SCOREBIAS tag in the xml reference. The SCOREBIAS tag can be used to view PatternScorer, DateBias or MetaData score of the search results. To see these values you must remove the "proxystylesheet" parameter from the search URL, this is also described here in the xml reference.
If the values presented are shown then the biasing should indeed be working, however if these values still can not be seen it's possible that you have not enabled biasing correctly. Please check that you have set a biasing policy for your front end under Serving > Front Ends > Filters
Workaround: Should you intend to sort results, then please try using the sort parameter, it is possible to sort by relevancy or by date. Please see the following documentation for further details.
Sort by relevance
Additional Information: Using Result Biasing to Influence Result Ranking
Known Issues: (ref. 6081241), the ScoreBias value for DateBias always returns VALUE="-1".
Versions affected: All.
Versions fixed: Unfixed.