Tuning rank is one of those things you have to resort to when everything else you have tried fails. So far you haven’t been able to create custom rank models in SPO, but at SPC12 there was a session called Optimize Search Relevance in SharePoint 2013 which mentions a method of tuning rank by judging the results for a set of queries to tune the model.
In addition to judging queries and results you may add one of five rank features to your model.
|Ranking Feature Type||Description|
Suggested feature based on judged queries
|The app can suggest features to add when feature vectors have been extracted for a sufficient number of judged documents. Suggestions will be rank features that have a strong correlation (negative or positive) with the relevance judgments provided by the automated tuning. This option is only available after you have run automated tuning on this ranking model at least once. See more about automated tuning later in this article.|
Searchable text managed property
Choose a managed property to be used in the search result ranking calculations.
If you select that proximity of query terms in the property value is important, you can later enter a Proximity weight for the feature. The app uses the variants isExact=1 and isDiscounted=1.
Sortable numeric managed property
Also called static rank feature.
The managed property must be of type Integer. The app uses the Rational transform.
Choose a managed property, and enter a default value for the property. The default value will be used if an item doesn’t have a value explicitly set.
Sortable property with a specific value
Also called bucketed static rank feature. Choose a managed property, and enter the default value for the property.
Having value: This number is the specific bucket that is being tuned.
Ranking feature from the base model
|Use this option to tune the weight of existing features. Choose between existing rank features.|
By looking at the above it doesn’t look like you will be able to add Freshness to your ranking with this App.
This app will also be part of David Hollembaek’s and my presentation at SPC14 – Managing Search Relevance in SharePoint 2013, but the caveat is that the App has yet to be released to the App store, but I’ve been told it should be out in a month or so, and then be available for on-premises in April.
The good part is that the documentation is available, so you can get a heads-up on how to use this new rank tuning App. Head over to http://office.microsoft.com/en-us/office365-sharepoint-online-enterprise-help/create-a-custom-ranking-model-by-using-the-ranking-model-tuning-app-HA104104860.aspx for a peek and stay tuned for the App itself.