India - Annual Survey of Industries: 2011-12

The sampling design adopted in ASI has undergone considerable changes from time to time, taking into account the technical and other requirements. The present sampling design has been adopted from ASI 2007-08. All the factories in the updated frame are divided into two sectors, viz., Census and Sample.

For ASI 2007-2008, the Census Sector has been defined as follows:
a) All industrial units belonging to the five less industrially developed states/ UT's viz. Manipur, Meghalaya, Nagaland, Tripura and Andaman & Nicobar Islands.

b) For the rest of the twenty-six states/ UT's., (i) units having 100 or more workers, and (ii) all factories covered under Joint Returns.

c) After excluding the Census Sector units as defined above, all units belonging to the strata (State by 4-digit of NIC-08) having less than or equal to 4 units are also considered as Census Sector units.
Sample Sector: From the remaining units excluding those of Census Sector, called the sample sector, samples are drawn circular systematically considering sampling fraction of 20% within each stratum (State X Sector X 4-digit NIC) for all the states. An even number of units with a minimum of 4 are selected and evenly distributed in two sub-samples. The sectors considered here are Biri, Manufacturing and Electricity.

Selection of State Samples: After selecting the central sample in the way mentioned above, the remaining units in the sample sector are treated as residual frame for selection of sample units for the States/UTs. Note that for the purpose of selecting samples from the residual frame for the State/UTs, stratification is done afresh by grouping units belonging to District X 3- digit NIC for each state to form strata. The sample units are then drawn circular systematically from each stratum. The basic purpose of introducing the residual sample was to increase the sample size for the sample sector of the states so as to get more reliable estimates at district level.
Validated state-wise unit-level data of the central sample are also sent to the states for pooling this data with their surveyed data to get a combined estimate at the sub-state level.

The sampling design adopted in ASI has undergone considerable changes from time to time, taking into account the technical and other requirements. The present sampling design has been adopted from ASI 2007-08. All the factories in the updated frame are divided into two sectors, viz., Census and Sample.

WGT (Multiplier Factor) is the weighing variable from Block A : Identification Block.
For Census data WGT has been given weight as 1.