The data used to identify how your affiliates have affected your store is saved within a database.  This data is indexed in order to make the search for this information much quicker.  However, there are times when you have made a change to your affiliates and the index must be refreshed. The option of indexation allows you to take care of this need, basically updating the index to the latest changes.  The following tutorial shows how to use indexation in PrestaShop 1.5.

Refreshing the Index for Affiliates in PrestaShop 1.5

1. Login to the Administrator as an Administrator
2. Hover over menu bar where it says STATS - click on REFERRERS when it appears at the bottom of the drop-down menu.
3. You will see the following screen:
   
   
   
   
4. Click on REFRESH INDEX in order to update the index for your affiliates

Note that you when you use the option to update your index for your affiliates, it may take awhile since the database may be fairly large.  Make sure you use this option if you need to apply changes - such as as the affiliate fees.