in order to determine the comparable set the quality rating is based on many  features which can be divided over  major categories i facilitiesamenitiesservices offered by the accommodation on bookingcom ii property configuration such as unit size number of rooms and occupancy iii number and quality of the photos uploaded by the accommodation iv average guest review score as well as some subscores for example cleanliness as those are proven to be particularly helpful for customers in assessing the quality of certain accommodations and v anonymised and aggregated historical booking data for example to assess the star rating of booked accommodations