The NSO said it would use 2006 as the new base year for the computation of the CPI. It currently uses the year 2000.

With the revision, NSO said the weight of food and non-alcoholic beverages in the CPI will decrease to 38.98 percent in the 2006 base CPI from 41.49 percent in the 2000 base.

The weight of rice also declined to 8.92 percent from 9.36 percent.

Similarly, the share of housing, water, electricity, gas and other fuel, the second highest group, dropped to 22.47 percent in 2006 from 23.70 percent in 2000.

Expenditure on rentals and materials for the maintenance and minor repair of dwelling were lower, while those for water and electricity were higher.

Six major groups, however, increased their shares in the 2006 CPI weights. Transport gained the biggest increase at 2.22 percentage points to 7.81 percent from 5.59 percent brought about by higher expenditure share in passenger transport by road.

It was followed by restaurant and miscellaneous goods and services which went up by 1.49 percentage points to 12.03 percent from 10.54 percent because of bigger weights in meals, snacks, drinks and refreshment purchased outside the home and that of personal care items. The weight of the other four groups went up by less than one percentage point.

"Economic, social and technological changes may have influenced Filipinos. Tastes and preferences and these, in effect may have resulted in changes in the consumption patterns of the population," NSO said.

"As household expenditure patterns vary (they tend to spend less on some items and more on others), weights are used to ensure that the CPI reflects the relative importance of each item or group of items in the market basket. The weights are expressed as a proportion of household expenditure for an item to the total national expenditure," the agency said.