The source writes:
Data are disseminated on the Industrial Production Index (IPI), a Laspeyres index (average month of 2015 = 100).
The index measures production volumes and covers the mining and quarrying, manufacturing, electricity, gas and water supply sectors. The data are obtained from an exhaustive survey of enterprises with 20 and more employees, a selected sample of enterprises with up to 19 employees and a predominance of industrial activity, and a selected sample of enterprises with non-industrial activity.
The weights are based on the 2015 annual data on added value (derived from the annual structural survey) and on the 2015 cumulative monthly data on production by value, (derived from the monthly survey on production by value). The change of the index base and weights revision is done based on the year 2015.
Data are published for the whole Slovak Republic, sections, special aggregates of the industrial branches, according to NACE Rev. 2 classification system.
Industrial production indices have been seasonally adjusted by the DEMETRA software and are revised backwards from the beginning of the time series. Data adjusted of number of working days and raw data are published in database SLOVSTAT (http://www.statistics.sk).
- Concept: Short-term indicator of volume change in industrial production. The purpose of the index is to provide quick information on the monthly change in global industrial production and to signal any fundamental changes in development of particular industrial activities.
- Definition: Measure of change in the volume of industrial output, based on a selection of enterprises and products. The methodology used is in conformity with EU standards.
Classification: Enterprises are classified according to their principal activity by SK NACE Rev. 2. Products are classified according to PRODSLOV 2009, which is the national version of PRODCOM 2009 (before 1996, the JKPOV national classification).
Scope of the data
- Industrial coverage: The following groups are distinguished (a) All enterprises principally engaged in industrial activities (SK NACE Rev. 2 branches 05 - 39, covering mining and quarrying, manufacturing, electricity, gas, steam and air conditioning supply, water supply; sewerage, waste management snd remediation activities) and with 20 and more employees; (b) All enterprises principally engaged in industrial activities with less than 20 employees but more than 100 million SKK annual turnover; (c) Sample of small enterprises principally engaged in industrial activities not included under (a) or (b); (d) Sample of enterprises whose principal activity is non-industrial, but which produce industrial products as a secondary activity.
- Product coverage: All industrial goods and services (codes 05 through 35 (without 353) of SK NACE Rev. 2), including output for use within the enterprise itself (that is, intermediate consumption of another establishment within the enterprise or own-account capital formation).
Source data collection programs
- Nature of indicators used: Industrial production index is formed from 70 percent of products value expressed in units in kind and 30 percent of deflated output in value expression.
- Nature of weights: A two-stage weighting system is used. The first stage relates to the value added of enterprises in each 4-digit SK NACE Rev. 2 group 05-35 (without 353). The second stage, which refers to 6-digit aggregations PRODSLOV 2005 is based on output value of individual product representatives within each of the stage one groups.
- Sources of weights: Annual survey of the production structure of enterprises, supplemented by cumulative data from monthly industrial surveys.
- Period of current index weights: IPI's calculation is based on the change of volume of selected products and on the two-stage weight system. For weight specifying there are used data on value added from year enterprise survey for the year of 2005 and on producing of products in value expression from monthly industrial surveys for the year of 2005.
- Frequency of weight updates: Every five years (years ending with a 0 or 5), the next update for the year 2010 is expected in 2012.
- Item selection: The selected products should, in combination, at least cover 80 percent of the output value in each 4-digit SK NACE Rev. 2 branch. The actual coverage is circa 85 percent of total industrial output.
- Unit selection: Large industrial enterprises in terms of staff or turnover are surveyed integrally; small enterprises and enterprises with secondary industrial activities are sampled. The sample includes all enterprises whose industrial output is more than 50 % of the average enterprise output in relevant branch of industry.
- Sample sizes: The number of large industrial enterprises in terms of staff is about 2867. The number of selected small enterprises is about 74; the number of selected non-industrial enterprises is about 34. The number of product representatives at the 6-digit level is 470.
- Data collection methods: Mail questionnaire. The large majority of enterprises receive questionnaires with prewritten codes; some new enterprises fill out blank-box questionnaires.
- Item/product specification: Products are specified according to 10-digit PRODSLOV 2009 codes.
Source data statistical techniques
- Computation of lowest level indices: Quantity of output of the individual representative item relative to its average monthly output in the base year.
- Aggregation: Laspeyres index.
- Alignment of value of weights and base period: Not applicable.
- Linking of reweighted index to historical index: Not applicable.
- Reference period: Average month of 2015 = 100.
- Procedures for non-response: Non-response is about 10 percent. No specific procedures are in place apart from those concerning missing observations (see below).
Other statistical procedures
- Treatment of missing observations: The missing data for the reference month are replaced by data from the previous months, maximum during three months.
- Selection of replacement items: Not applicable.
- Adjustments for quality differences: No adjustments for quality differences are made.
- Introducing new units and products: Reporting units are able to indicate new products in a blank box on the questionnaire. On the basis of this information, the individual enterprise questionnaire may be updated twice a year. New products (classified at the 10-digit level of PRODSLOV) are introduced without effects on the weighting scheme (6-digit level representatives).
- Seasonally adjusted indices: Indices are published not adjusted, adjusted from the influence of number of working days and since 2000 seasonally adjusted indices realised by the DEMETRA software. While processing the last month of each quarter, data has been revised backwards from the beginning of the time series.
Moody's Anlaytics supplements
For the general index, we back-extend (1993m1 to 2007m12) and construct a seasonally adjusted counterpart.