 Items registering a greater than average price increase (or smaller decrease) become relatively more important.This two-stage method is relatively new.Before 1999, CPI used only Laspeyres indices, measures of the price changes in a fixed market basket of consumption goods and services of constant quantity and quality bought on average by urban consumers, either for all urban consumers (CPI-U) or for urban wage earners and clerical workers (CPI-W).