The increase in the retail prices of construction materials in Metro Manila slowed in September, the Philippine Statistics Authority (PSA) said.

PSA data released Tuesday showed that the construction materials retail price index (CMRPI) in the National Capital Region (NCR) increased at a slower rate of 1 percent from 1.1 percent in August.

The PSA attributed the downtrend in the annual growth rate of CMRPI during the month to the annual decrease in the index of carpentry materials at 0.1 percent in September from an annual increase of 0.3 percent in the previous month.

The slower increase in plumbing, electrical, masonry, and miscellaneous construction materials also contributed to the downtrend in the CMRPI.

The CMRPI measures the changes in the average retail prices of construction materials.

Retail price refers to the price at which sellers accept orders for spot or earliest delivery, which are usually in small quantities.

The criteria for selecting sample stores include the popularity of an establishment along the line of goods to be priced, consistency, completeness of stock, permanency of outlet, and geographical location.