The Conference Board’s Employment Trends Index slipped in August, following increases in June and July. The index stood at 128.02 in August, down from 128.44 in July. The August rating represents a 0.8-percent increase over the same month last year, however.

“The Employment Trends Index is consistent with moderating job growth in the second half of 2016,” says Gad Levanon, chief economist, North America, at The Conference Board. “With the ongoing massive retirement of baby boomers, even moderate job growth is enough to continue to tighten the U.S. labor market.”

In calculating its Employment Trends Index, The Conference Board aggregates eight labor-market indicators that it considers accurate in their own areas. Aggregating individual indicators into a composite index filters out “noise,” revealing underlying trends more clearly. The indicators come from the U.S. Department of Labor, the U.S. Bureau of Labor Statistics, the Federal Reserve Board and other sources.

The August decrease is attributed to seven of the eight components returning negative results. In order from the largest negative contributor to the smallest, these were: percentage of respondents who say they find “jobs hard to get,” ratio of involuntarily part-time to all part-time workers, job openings, initial claims for unemployment insurance, industrial production, real manufacturing and trade sales, and the number of employees hired by the temporary-help industry. Also included in the index is the percentage of firms with positions they are currently unable to fill, reported by the National Federation of Independent Business Research Foundation.