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Statistical processing

Contact info

Statistics Denmark, Short Term Statistics
Erik Slentø
+45 3917 3088

esl@dst.dk

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Construction Survey

Monthly business survey data is collected from a sample of approximately 800 enterprises. Data is reported either online at http://www.VIRK.dk or in paper questionnaire, and consists of qualitative information about changes in net sales, employment, prices, orders, etc., which are not validated. The collected data are enumerated from the sample to the total population weighted by employment data, and distributed at industry and size groupings. If seasonal variation patterns are detected for the indicators that constitute the composite confidence indicator, data is adjusted for this.

Source data

The statistics are compiled from data collected via questionnaires. The sample is based on information in the Central Business Register.

The survey is carried out with a panel based stratified sample consisting initially of 800 enterprises representing about 27 pct. of the total number of full-time employees in selected trades. Because of drop-out the sample is updated one or two times a year. Typically the sample is added 150-200 new enterprises at update.

The sample is stratified into industry groupings and size groups in terms of full time employees.

The industry strata are defined by (NACE rev.2 classification system figures in brackets):

  • F Construction
  • 41000 Construction of buildings
  • 42000 Civil engineering
  • 43201 Electrical installation etc.
  • 432200 Plumbing, heat and air-conditioning installation
  • 43301 Joinery installation etc.
  • 43302 Painting and Glazing etc.
  • 439910 Bricklayers
  • 43003 Other specialized construction activities etc.

The three size strata are defined by:

  • above 50 employees
  • 10-49 employees
  • 1-9 employees

The primary data are stored at the level of business establishment (workplace). The following data are available:

  • File no. (workplace)
  • ID of the business establishment
  • Data on addresses
  • Employment
  • Kind of activity
  • Year
  • Month
  • Trends, actual *
  • Trends, expected *
  • Assessment at the end of the month **

*This applies to the following variables: employment, sales and prices.

**This applies to the following variables: volume of orders and reductions in the production.

Frequency of data collection

Data is collected each month during the first 2-3 weeks.

Data collection

Data is collected either by paper questionnaire send to the respondent including postage pre-paid envelope, or by online reporting. In the latter case, respondents receive an e-mail notification telling it is time to log in to the reporting system VIRK, and fill the online questionnaire. Respondents are urged to respond online.

Response rate is about 79 pct. on average. Deadline for responding to the current month's questionnaire is about the 6th of the month. Here, about two third of the answers have arrived. The rest, one third, arrives within two weeks and are included in the statistics.

Reminder is send about the 13th giving new deadline about the 20th of the survey month.

Information to the respondents about the statistics is found here (in Danish).

Data validation

To fill the questionnaire one have to tick mark one of three options for each question. This does not call for data validation. The paper questionnaires are scanned automatically, and questionnaires refused in this process is handled manually.

Non-response errors are corrected for in the enumeration process.

By online reporting the system warns the respondent if a question is not ticked. However in both cases, online reporting or reporting by mail, it is accepted that some questions are left un-ticked. In data compilation process basic data is checked if bigger changes from last month is observed - usually the reason is either unidirectional change in assessments by several big companies or missing reporting from some few big companies.

Data compilation

The enterprises' responses are weighted according to the average number of full-time employees. Within each stratum answers are distributed into percentages answering decline, unchanged and increase adding up to 100 pct. The group of non-responding enterprises within the stratum is assigned same percentage distribution as the group of responding enterprises (which is considered a imputing method).

Hereafter, the responses are enumerated to the number of full-time employees of the total population, within each industry-grouping.

Confidence indicator for a variable is calculated and denominated balance. Is is the difference between percentages of enterprises (weighted by number of employees) that have answered increase and decrease. The balance figures do not measure the size of the increase or decrease, but only indicates that an overweight of enterprises expect either increase or decrease.

The Composite confidence indicator is the arithmetic average of balance figures for expected employment and current level of order books.

Especially regarding the questions on Production limiting factors, e.g. lack of workforce, the indicators reflects the share of companies that have ticked of the specific questions. The share of companies is weighted according to the average number of full-time employees within the specific companies. Hereafter the result is enumerated to cover the full population within each industry grouping.

Adjustment

No adjustments are carried out, besides seasonal adjustment.