Dokumentation og international benchmarking af bygge - Danmarks ...

The representativity of the construction types included in the index comparedto the demanded use of the index is thus a significant issue.Matched models methodComponent cost methodThe matched models method can be considered the least complicatedmethod, but there is a big concern regarding how representative themodel is compared to the required use of the index.The selection of construction types must be revised periodically in order toensure a continuously representative sample compared to the requireduse of the index. Furthermore, with the component cost method also theconstruction components, that are priced, need to stay representative ofthe methods actually used in the construction industry.To be able to preserve a representative sample of subcontractors’ services,knowledge of the construction industry is required. Here great help can begained from Eurostats compilation of price level indices for constructionin the frame of the PPP programme 12 . In that way, it will not be needed tomaintain this expertise within Statistics Denmark.Hedonic methodThe selection of construction types must also with the hedonic methodbe revised periodically in order to ensure a continuously representativesample compared to the required use of the index.Furthermore, with this method the regression model needs to be checkedperiodically to make sure that the model fit is as good as possible, meaningthat the variables included represent the cost bearing elements of theconstruction.Comparability over timeFor all three methods, it takes an effort to continue having comparabilitybetween the building or building components priced in one period and theones priced in the following period.Component cost methodQuality adjustments must be undertaken continuously. Bigger changes inthe quality of the service and changes in the conditions of the performanceof the construction component demand an adjustment of the achievedmarket price in a way that the art and the quality of the construction componentis the same as it was in the previous period.In the cases where the services underlying the construction componentdeviates significantly in its performance and the conditions under whichthe service was conducted deviates significantly from the previous period,the construction component should be changed The new constructioncomponent should be exhaustively described as it is currently performedand is expected to be performed in the future. The builder is also asked toreport the price for the new component and to estimate the price for the12 Purchasing power parities programme (ECP- European Comparison programme) measures and compares theprice levels of construction industries in and among European countries applying component cost method.102