Dokumentation og international benchmarking af bygge - Danmarks ...

• Ventilation and heating systems• Sauna• Roofing• Terrace• Central vacuum cleanerStatistics Sweden has chosen to divide the explanatory variables into twogroups. The first group consists of quality variables and describes: Areas,equipment standard, constriction joists, roof and outer wall, heating systemetc. This group of variables includes both dummy variables and continuousvariables. The second group consists of shift variables, describesgeographic site and development/reconstruction area.Variables includedNorway - The explanatory variables used in the regressions analysis whencalculating the new detached house index are presented above, and themost important is the utility floor space. The relation between the priceper square metre and floor space is not linear. The logarithm of floor spacegives approximately a linear relation, and less variance for the estimatedcoefficient. Other numeric variables are number of bathrooms and numberof WCs. Most variables in the equation are dummy variables or classificationvariables like ground quality, type of heating and ventilation,roofing etc. Some variables like location and category of loan are not directlylinked with the quality standards of the houses but to some extentinfluence the variations in prices. These variables are treated as dummyvariables. The price per square meter was chosen as the dependent variableinstead of the price per dwelling because of the problem of heteroscedasticity.It appears that the price variation increases with the size ofthe dwelling.Statistics Sweden’s objective has been to collect as few variables as possibleand only variables that are easy for data providers to prepare, withoutnegatively affecting the quality of the statistics. Since the geographic locationof a project is of great significance for the end price, an auxiliary variable– average square meter price for value area of real estate per municipality- is included to ease the geographic division of construction projects.More variables are used when calculating regression coefficientsthan when making quality adjustments. In addition, Statistics Sweden hasdecided to construct two separate models, one model for multi-dwellingbuildings and one for collectively built one and two-dwelling buildingsand hence they include different explanatory variables.Definition and collection of dataDefinition of the mainconcepts and variablesIn Norway, the price used is what the investor has to pay for a new detachedhouse, excluding site value, or cost such as connection to road,water and sewer services, duties and administration fees, and interest onbuilding loans. VAT is included in the price even though it diverges from93