The government has decided to include natural gas and fertilisers in the list of core sector infrastructure industries, a move which will help in capturing performance of economy in a better way.
Currently, the government evaluates performance of six key sectors - crude oil, petroleum refinery, cement, electricity, finished steel and coal - on a monthly basis.
The new series, which will have data for eight key sectors, would be released on June 10, an official told PTI.
"Now we will add two new categories - natural gas and fertilisers. The addition will increase the weight of the core sector to about 37% in the IIP," the official added.
Presently, the six infrastructure industries have a weight of 26.7% in the overall Index of Industrial Production (IIP).
On June 10, the government would also come up with the new index to measure the factory output. The base year for the new IIP series will be changed to 2004-05 from 1993-94.
"The new IIP numbers will give the weight for these two categories," the official said.
According to experts, the new IIP series will reflect the industrial scenario better as a result of the change in the base year for the benefit of policy makers and market participants.
The expansion of core sector list follows similar measures undertaken for computation of Wholesale Price Index (WPI) and IIP.
The new WPI series, with base year 2004-05 and launched in September, 2010, has 241 more items than the old index. The WPI now measures a total of 676 items against 435 earlier.
The output of the six core infrastructure industries grew by 7.4% in March 2011, an improvement from the 6.8% expansion clocked an year ago.
For the 2010-11 fiscal, the key infrastructure sectors expanded by 5.9%, as against 5.5% in the previous year.
Department of Industrial Policy and Promotion (DIPP), an industry ministry arm, releases the core data.