Zillow Observed Rent Index (ZORI): This index represents a balanced assessment of the average market rent in a specific area. It's a repeat-rent index, carefully adjusted to reflect the composition of the rental housing market, thus providing a comprehensive view beyond just the currently advertised rental properties. ZORI calculates this measure in monetary terms by determining the average of rent prices within the 40th to 60th percentile for all types of homes and apartments in a region, with this average being adjusted to accurately represent the rental housing stock.