The so-called Section 8 housing program under the United States Housing Act of 1937 (Housing Act) authorizes private landlords who rent to low-income tenants to receive "assistance payments" from the Department of Housing and Urban Development (HUD) in an amount calculated to make up the difference between the tenants rent payments and a "contract rent" agreed upon by the landlords and HUD. Section 1.9b of the latter parties "assistance contracts" provides that contract rents are to be adjusted annually by applying the latest automatic adjustment factors developed by HUD on the basis of particular formulas, while 1.9d specifies that, "[n]otwithstanding any other provisions of this Contract, adjustments as provided in this Section shall not result in material differences between the rents charged for assisted and comparable unassisted units, as determined by the Government . . . ." In the early 1980s, HUD began to conduct independent "comparability studies" in certain real estate markets where it believed that contract rents, adjusted upward by