In order to improve recommender accuracy for the specific product, we would need to collect actual data from people wearing the product. 

Now you can provide those data in the form of "User Match" in the app.

In the size chart > recommender, you will see a "User match" button

Clicking on it will open the User Recommender Match dialog.

First we need to add user profile, so click on "Add User", then provide the basic info for the person

Click "Create", then you will see the person show up in the list.

Next click on "Add match" to provide let us know what size this person should wear for the size chart 

After creating a user match, you will see the person show up in the "matched users" table. The selected size will show up as "Ideal size", and the current recommended size from the recommender will show up as "Recommended Size"

We are currently iterating on this feature and developing a new version of the recommender that can further optimize based on the data provided here.