# Building cost index: documentation of statistics

## Basic data of the statistics

### Data description

Of the types of buildings in the Classification of Buildings 2018 (intended use categories) four types of building projects have been formed for the building cost index: detached and semi-detached house, block of flats, service building and industrial and warehouse building. The project type detached and semi-detached house describes professional, producer-form construction of one-dwelling houses, two-dwelling houses and terraced houses. The project type block of flats consists of the classes block of flats, residential buildings for communities and dwellings for special groups. Service building represents the average project type of many different commercial, office, transport and communications, institutional care, assembly and educational buildings. Service building corresponds to the building project type office and commercial building of the previous base year. The type of project idustrial and warehouse building represents different industrial and warehouse buildings in the index.

### Statistical population

### Statistical unit

### Unit of measure

### Base period

### Reference period

The building cost index is published on the 15th day of the month following the reference month. If the day is on a weekend, the index is published on the previous weekday.

### Reference area

### Sector coverage

The building cost index does not cover all categories of the Classification of Buildings. Categories 02 Free-time residential buildings, 10 Energy supply buildings, 11 Public utility buildings, 13 Rescue service buildings, 14 Agricultural buildings and livestock shelters and 19 Other buildings are not taken into account in the official building cost index.

### Time coverage

The published index point figures of the building cost index are always final at the time of publication. After this, the figures are not changed apart from in exceptional circumstances.

### Frequency of dissemination

## Concepts

### Building cost index

### Building trade

### Independent building

### Input of supplies

### Labour input

### Other inputs

### Transfer price coefficient

The coefficient is calculated using the currently valid building cost index. Building cost indices of different years have their own product selections and weight structures. This ensures that the index measures correctly the structure of building costs prevalent at each point in time.

## Accuracy, reliability and timeliness

### Overall accuracy

The data collection for the building cost index is based on a judicious sample of representative commodities selected for monthly price monitoring. Price changes in these goods are monitored on the pure price index principle, i.e. by eliminating the price change due to quality changes from observed price changes.

The accuracy of the building price index is affected by possible sampling error and data processing errors. The magnitude of the errors has not been estimated.

The correctness of the indices is also influenced by non-response, which in the building price index is between four and five per cent on monthly level. Efforts are made to reduce non-response by reminding respondents to supply the requested data.

### Timeliness

The building cost index is published on the 15th day of the month following the reference month. If the day is on a weekend, the index is published on the previous weekday.

### Punctuality

### Data revision

The reason why data in statistical releases become revised is often caused by the data becoming supplemented. Then the new, revised statistical figure is based on a wider information basis and describes the phenomenon more accurately than before.

Revisions of statistical data may also be caused by the calculation method used, such as annual benchmarking or updating of weight structures. Changes of base years and used classifications may also cause revisions to data.

The data of the building cost index are not revised.

### Sampling error

Because there is a judicious sample in the statistics, estimating the sampling error is not relevant.

### Measurement error

Price changes in commodities selected to price collection are monitored on the pure price index principle, i.e. by eliminating the price change due to quality changes from observed price changes. The building products included in the data collection should be described and specified as precisely as possible. Then the price data of the monitored products are temporally comparable. If comparable data cannot be collected for successive periods for a certain product or the production of the product or the quality in question ceases, the old product can be changed to a new one flexibly in statistics production.

The magnitude of the possible measurement error has not been estimated.

### Non-response error

## Comparability

### Comparability - geographical

However, Statistics Finland also publishes more comprehensive data from the building cost index than required by the EU Regulation. For example, there are more building types than the international minimum level. In addition, renovation indices, index clause sub-indices and transfer price coefficients of residential building construction are published for national needs, so there may not necessarily be an international reference point for them.

### Comparability - over time

Long time series are published on the building cost index. The oldest overall index 1935 = 100 published in database tables is from 1922 onwards (annual data only).

## Source data and data collections

### Source data

The data collection collects price data from producers of building materials and various wholesale and retail trade stores. The distribution route of the inquired products is taken into account in the weight structure of the building cost index. The same product is generally asked from different distribution channels in the supply chain and price changes collected from different sales locations are weighted with the distribution weights defined for each product. The following distribution routes (by order of numbers of observations) have been taken into account in the building cost index:

1. Delivery from factory

2. Hardware store

3. Installation wholesale firm

4. Electrical supplier wholesaler

5. Timber firm

6. Paint, wallpaper and tile store or other special store

7. Household appliance store

8. Other (e.g. importer)

Data on the cost index of civil engineering works, the consumer price index, the producer price index for services and the producer price index are also utilised in the calculation. To measure labour costs, the index of wage and salary earnings is used, to which social costs updated once a year from employer organisations are combined.

The calculation of the building cost index is based on a total of around 1,100 prices from approximately 260 data suppliers.

### Frequency of data collection

## Methods

### Data compilation

The building cost index is calculated in accordance with the Laspeyres index. The weights of the index are from the base period and they are kept fixed throughout the calculation period of the base year (around five years).

The total index of the building cost index is calculated as the weighted (geometric) average of four house project types. The weight of the house project type in the overall index is determined by the value of building production by building type derived from Statistics Finland's statistics on building and dwelling production.

A separate input distribution has been defined for each house type project. Inputs are measured with one or more products. The distribution routes previously presented are taken into account in weighting between products and product groups. The distribution routes of the product and their weights vary from one product to another, but factory suppliers, as well as installation and electrical supplier wholesalers are most significant as a whole.

The expert help of VTT Technical Research Centre of Finland and several data sources have been used to define the input weights inside the project types. The VTT report (in Finnish) describes the latest weight structure 2021=100.

### Data validation

### Documentation on methodology

The VTT Building Technology’s publication relating to the Building Cost Index 2000 = 100 has also been published on the methodological descriptions page of the statistics (in Finnish).

## Principles and outlines

### Contact organisation

### Contact organisation unit

### Legal acts and other agreements

Statistics Finland compiles statistics in line with the EU’s regulations applicable to statistics, which steer the statistical agencies of all EU Member States.

Further information: Statistical legislation

The production and data content of the building cost index are guided by EU regulation 2019/2152 on European business statistics.

### Confidentiality - policy

Further information: Data protection | Statistics Finland (stat.fi)

### Confidentiality - data treatment

### Release policy

Further information: Publication principles for statistics at Statistics Finland

### Data sharing

### Accessibility and clarity

### Data revision - policy

Revisions – i.e. improvements in the accuracy of statistical data already published – are a normal feature of statistical production and result in improved quality of statistics. The principle is that statistical data are based on the best available data and information concerning the statistical phenomenon. On the other hand, the revisions are communicated as transparently as possible in advance. Advance communication ensures that the users can prepare for the data revisions.

The reason why data in statistical releases become revised is often caused by the data becoming supplemented. Then the new, revised statistical figure is based on a wider information basis and describes the phenomenon more accurately than before.

Revisions of statistical data may also be caused by the calculation method used, such as annual benchmarking or updating of weight structures. Changes of base years and used classifications may also cause revisions to data.

Seasonally adjusted data in statistics on economic trends become revised because of the calculation method used. Additional information on a new time series observation is exploited in model-based calculation methods and this is reflected as changes in previous releases. Revisions of the latest figures to be seasonally adjusted are elaborated on in the releases and quality reports of statistics.

A summary table of the revisions that have taken place is also published in connection with key statistics on economic trends and some annual statistics. The table shows how the data for the statistical reference periods have changed between the first and the most recent statistical release.

### User needs

The building cost index is used to deflate inputs in national accounts and the indices of renovation building of residential building construction are used as source data in the consumer price index, for example. The building cost index and its index-clause sub-indices (P2000=100) have been used as a compensation index for building projects. The revision indices currently used in contract agreements can, however, be freely agreed upon. The building cost index is still used for the time being as a revision index in real estate taxation when updating the base value of the taxable values of buildings. Many insurance premiums are also tied to the building cost index. A transfer price coefficient tied to changes in the building cost index is used in the maximum price calculations of government-subsidised dwellings. The building cost index can also be used in the maximum price calculations of price controlled HITAS dwellings.

### User satisfaction

### Quality assessment

### Quality assurance

Quality management requires comprehensive guidance of activities. The quality management framework of the field of statistics is the European Statistics Code of Practice (CoP). The quality criteria of Official Statistics of Finland are compatible with the European Statistics Code of Practice.

Further information: Quality management | Statistics Finland (stat.fi)

### User access

Further information: Publication principles for statistics

Unless otherwise separately stated in connection with the product, data or service concerned, Statistics Finland is the producer of the data and the owner of the copyright. The terms of use for statistical data.