It captures movement of prices of all commodities in all trade and transactions.

WPI is available on a weekly basis with the shortest possible time lag of two weeks.

Thus, it is widely used in business and industry circles and in government and, is generally taken as an indicator of the rate of inflation in the economy.

It was in July 1989 that the current series of WPI with the base year of 1981-82 came into existence.

To reflect the current changes taking place in the economy the government had appointed a working group to revise the existing WPI series and to examine the commodity coverage, selection of the base year, weighting diagram and other related issues.

The new series with a base year of 1993-94 has as many as 435 items in the commodity basket.

To reflect the structural changes in the economy a lot many commodities have been added and few unimportant ones have been dropped out.

In the revised series, primary articles contribute 98 items, fuels, power, light and lubricants 19 items and manufactured products provide 318 items.

The number of price quotations in the revised series is spread out to as many as 1,918 quotations.

In all, there are 136 new items included in the revised series.

Of this, primary articles account for 13 nos, the fuel group contributes one while the manufactured products have 122 new commodities.

In the revised series the fuel, power, light, lubricants and manufactured products have a higher weightage as compared to the 1981-82 series whereas the primary products appear much lower in the list.

Primary products
weightage of 22.02 as compared to 32.30 in the old series. For fuel, light and lubricants it is 14.23 compared to 10.66 earlier. For manufactured goods it is 63.75 as against 57.04 before.

The new series starts at a higher level accounting for a relatively higher annual rate of change in contrast to the earlier series. But thereafter, the two series virtually move in tandem.