A quantity index measures the level of quantity produced, assuming the price does not change due to inflation or deflation. An advantage of chain-type quantity indexes is that they can easily be re-based to a new base year because these indexes are not subject to bias depending on the base year selected. To re-base the quantity index series, simply divide every quantity index value in the series by the quantity index value of the desired new base year. This will set the value for the new base year equal to 1.00, and all other indexes in the series will be re-based to the new base year. To convert to the usual index number format, multiply all numbers in the series by 100.

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