Homeowners' Dwelling Characteristics

owner-occupants in duplexes or multipleunit structures likely possess a different amalgam of housing consumption versus investment motives than the traditional homeowner. And owneroccupied single-family units that are mobile homes, row- or townhouses, or condominium apartments undoubtedly possess quite different technological "transformation functions" for converting upkeep investments into improved housing quality.

But in addition to this implicit control there are several other explicit variables employed to control for various features of the dwelling that are likely to affect the occupying homeowner's evaluation of the structure and investment in it. These variables measure various aspects of the age, structural features, and size of the dwelling.

Differences in dwelling age typically imply differences in architectural style, construction technology, type and efficiency of mechanical systems (plumbing, heating, and wiring), and the time over which the structure has been subject to normal wear and tear, weathering, etc. Because these differences are not likely to be well modelled as a monotonic function, building age is measured instead by a set of categories representing distinct vintages of homes. Specifically, if the dwelling was built during the 1960-69 era, a dummy variable, BUILT60-69, is assigned the value one; zero otherwise. Similarly, if it was built from 1940-59, 1920-39 or before 1920, the dummy variables BUILT40-59, BUILT20-39 and BUILTPRE-20, respectively, are assigned the value one. Given this specification, the coefficients of these four structural vintage variables should be interpreted as the difference between the given vintage and that of a house built after 1969.

Although some structural features are measured implicitly by the vintage variables, others are measured explicitly by the following four variables. If the dwelling has an enclosed garage, the dummy variable GARAGE takes the value one, zero otherwise. If the dwelling has whole-house air conditioning, the dummy variable AIRCOND takes the value one, zero otherwise. If the dominant type of exterior construction consists of wood clapboard siding, the dummy variable WOOD takes the value one, zero otherwise. Finally, the absence of a central heating system is measured by the dummy variable NOHEAT.

The quantitative aspects of the dwelling package are measured by three variables. ROOMS measures the number of finished rooms of all kinds in the dwelling (excluding bathrooms). BATHRMS measures the number of bathrooms (including fractional) in the dwelling. YARD measures the street frontage (in feet) of the yard on which the dwelling is located. The relationship of these quantitative aspects of the dwelling to the size of the occupying household is measured by the given dwelling variable divided by the number of full-time residents (OCCUPANTS): the variables ROOM/ OCC, BATH/OCC and YARD/OCC, respectively.