In a study of housing demand, the county assessor is interested in developing a regression model to estimate the market value (i.e., selling price) of residential property within her jurisdiction. In addition, the assessor feels that there may be other important variables that will affect the market value of the house such as the size of the house, number of rooms, age and whether the house has an attached garage. These data for 15 randomly selected houses arc shown in the attached table.