Product popularity depends on many different parameters. For example how often a product (detail) page has been viewed, how often a product has been sold (online and/or offline), how often a product has been placed in the shopping cart, etc.
In the Tweakwise app you can use all these parameters to determine its relevance. These data are available when you are linked to Google Analytics. Read the article ‘How to read the metrics from Google Analytics’ for more information about all the metrics Tweakwise can request from Google Analytics.

Each product contains extra properties with values from Google Analytics. These properties can then be used in the sorting options to push the most popular products.