The National CPI measures the change in prices, on average, from month to month, of the goods and services bought by households, in Freetown, Bo, Kenema, Kono and Makeni and include all expenditure groups. Prices are collected for 400 items. All prices collected are the prevailing retail market prices from six (6) markets in Freetown and, three (3) Markets each in Bo, Kenema, Makeni, and Kono for weekly prices and other outlets for monthly items whose prices are less likely to fluctuate rapidly. We are using the Modified Laspeyres formula to compute indices according to the Classification of Individual Consumption by Purpose (COICOP) with 12 functions.