The index for shelter rose 0.3 percent in May and was the primary factor in the all items monthly increase. The food index increased 0.3 percent as both of its major components, the index for food at home and the index for food away from home also rose 0.3 percent in May. In contrast, the energy index declined 1.0 percent in May as the gasoline index fell over the month.

The index for all items less food and energy rose 0.1 percent in May, following a 0.2-percent increase in April. Indexes that increased over the month include medical care, motor vehicle insurance, household furnishings and operations, personal care, and education. The indexes for airline fares, used cars and trucks, new vehicles, and apparel were among the major indexes that decreased in May.

The all items index rose 2.4 percent for the 12 months ending May, after rising 2.3 percent over the 12 months ending April. The all items less food and energy index rose 2.8 percent over the last 12 months. The energy index decreased 3.5 percent for the 12 months ending May. The food index increased 2.9 percent over the last year.

A measure of the average change in prices over time for a set group of goods and services. The Bureau of Labor Statistics publishes CPIs for two population groups:

• (1) for all urban consumers (CPI-U) which covers approximately 80 percent of the total population
• (2) for all urban wage earners and clerical workers (CPI-W) which covers 32 percent of the total population.

Among the CPI components are the costs of housing, food, transportation, and energy. While the CPI is not technically a cost of living index, it is often used to indicate changes in the cost-of-living.

For more assistance, call the Boston office of the Bureau of Labor Statistics at 617-565-2327.