• Production index is the relative indicator which characterizes changing of product volume produced in comparison periods. Its main purpose is to provide a measure of the short-term changes in value added over a given reference period.
• Calculating of production index is realized on 4 stages: In the first stage the physical volume indices are formed by means of comparison of representative products' output (average annual prices of base year) that are estimated with the same prices in cash and kind during compared periods by semi fields; in the second stage the indices by all semi fields which made each extended industrial fields are generalized based on aggregation to get indices on extended fields. In the third stage calculating of physical volume index on industry is led by summarizing of index by extended industry fields. In the fourth stage, the corrections and additions are added to physical volume index of industrial products' production that was calculated based on representative commodities taking into the account of services and production-based works.
• The industry products are chosen on the basis of Statistic Classification of Industry Products (international PRODCOM classification) and industry activity-Economic Activity Types Classification (international NACE Rev 2 classifications - new version).

• To calculate, whole industry divides subfields and each field divides semi-fields (on the level of 3 digits by NACE). Industry fields of mining, manufacturing and electric energy, distribution of gas and water are used in the calculating of index.
• Representative commodity (each field at least 70% share having on types of products each month more than 400 industry product) basket which made according to each semi fields is assumed.

• The activity of industrial enterprises is completely based on statistical observation.
• The enterprises are registered by the area where actually functioned.

• While calculating, index of industry production is based on in kind data on the types of produced products and then calculates by aggregating to total industry index. The indicator of value-added of basis period is used during aggregation. In case of occurred strictly changes in the structure of field appropriate amendments are done in the weights of base periods.
• In the monthly product index, the data received in the result of observation of products that are produced by medium and large enterprises (by 726 enterprises, volume of annual turnover of which is more than 500 thousand manat and number of employees is 1-49 persons) is covered by all industry enterprises (by 2800 enterprises) annually and quarterly.
• The data is represented at official statistical reports and presented to national statistical bodies directly or with post by registration units and national statistical bodies send information to SSC by e-mail. A few numbers of enterprises present the reports by e-mail.

• The rule (a Laspeyres index) of aggregating base index is used to calculate index.
• All enterprises report monthly data. Rarely the data on previous month is chosen if the report data left or doesn't present the rule of automated conditional calculations and imputation methods aren't applied.
• The fields of industry -amendments are made taking into account of seasonal factors on B, C, D and E sections