India - Annual Survey of Industries: 1997-98

Sampling Procedure

The sampling design followed in ASI 1997-98 is a circular systematic one. All the factories in the updated frame (universe) are divided into two sectors, viz., Census and Sample.

Census Sector: Census Sector is defined as follows:

a) All industrial units belonging to the 12 less industrially developed states/ UT's viz. Manipur, Meghalaya, Nagaland, Tripura, Sikkim and Andaman & Nicobar Islands etc.
b) For the rest of the states/ UT's., (i) units having 200 or more workers and also some "Significant Units"were identified from the databases of ASI 1993-94 to ASI 1995-96, which although having less than 200 workers, contributed significantly to the Value of Output in these ASI years. and (ii) all public sector undertakings (PSU) and electricity sector were included in the census sector.

Remaining units, excluding those of Census Sector, called the sample sector, are arranged in order of their number of workers and samples are then drawn circular systematically Sampling technique from each stratum (State X 3-digit NIC) with a minimum of 4 samples per stratum.

The census and sample sectors were such formulated that the Census Sector units comprising at most 9% units contributed at least 90% of Net Value Added (NVA) at All-India level. Alternaitively, the sample sector comprising 91% industrial units contributed less than 10% of NVA.
The sample size n from the above sample sector was determined at All-India level first. Then the total size for a particular state was allocated in the proportion of total output in that stratum.
It may be noted that the sample size in stratum was always taken as an even no. (by adding on unit in case, it was odd) and if, sample size alongwith the no. of census units in any stratum be less than 4, then that stratum was merged with the units of a nearest stratum.

There was no deviation from sample design in ASI 1997-98

Please note that an inflation factor (Multiplier) WGT is available for each unit against records belonging to Block I: Products/By-Products Block Record type 81), for ASI 1997-98 data. The multiplier is calculated for each stratum (i.e. State X NIC-04 (4 Digit) after adjusting for non-response cases.

HOWEVER, IT IS TO BE NOTED THAT ALL THE INDUSTRIES (RECORDS) ARE ALREADY WEIGHTED BY MULTIPLIER FACTOR-WGT so there is no need for further multiplication.