Dokumentation og international benchmarking af bygge - Danmarks ...

nents. In Germany, reporting of the prices for compilation of output priceindex is compulsory.In Switzerland, e.g. the questionnaires are sent to about 6 400 constructioncompanies (including architects, engineers, insurance companies andbanks), out of which approximately 2,400 participate in the survey on thevoluntary basis. The number of individual prices on average per surveyperiod is about 30,000.Generally, the number of prices per construction type depends on the concentrationof businesses in the respective branch, on seasonal factors andon the good will of respondents.Respondent burdenGenerally, an effort is made to reduce the basket of the priced constructioncomponents in order to reduce the respondent burden. Hence, theconstruction components that have a negligible weight are left out fromthe questionnaire.Furthermore, in order to reduce the respondent burden synergies betweenthe baskets of construction components for residential buildings and nonresidentialbuilding constructions were determined. Hence identical constructioncomponents for the two construction types in building constructionwere identified and only surveyed once via a tailored questionnairefor building construction. Prices are then included separately into the respectiveindex (construction of residential buildings and construction ofnon-residential buildings respectively) according to its weight. This is thepractice in all studied countries.In Austria, the survey for construction output prices for building constructionhas a respondence rate of more than 90% and is thus one of the mostsuccessful voluntary surveys. Nearly 80% of the respondents, who reportsprices for building construction, are asked to fill in only 1-5 price information.In Germany in average each construction enterprise report prices for sixconstruction components. However, the number of the reported prices isdependent on the size of the enterprise and can vary from one to 50prices.In Switzerland no data on respondent burden has been found.Description of the component cost methodCalculationsAs usually in many price statistics a Laspeyers index is compiled. This indexmeasures the price changes over time for a basket of constructiontypes that is defined in a base period and held constant in the subsequentmeasuring periods. The weighting structure is also held constant for acertain number of years. The Laspeyres price index is calculated using thefollowing formula:76