WASHINGTON — The National Restaurant Performance Index declined below 100 in November due to lower same-store sales and customer traffic levels, according to the National Restaurant Association. The R.P.I., which is a monthly composite index, was 99.9 in November, a decline of 0.8% compared with the R.P.I. from October.

“While the R.P.I.’s November decline was largely the result of softer same-store sales and traffic performances, it doesn’t necessarily mean the industry’s recovery is in peril,” said Hudson Riehle, senior vice-president of the N.R.A.’s research and knowledge group. “Like the economy as a whole, the restaurant industry’s road to recovery will be one with occasional bumps along the way. Overall, the economic fundamentals of the restaurant industry remain positive, which will likely lead to stronger sales results in the months ahead.”

The overall R.P.I. consists of two components — the current situation index and the expectations index. The current situation index was 98.7 in November, a decline of 1.3% when compared with October.

The expectations index, which measures restaurant operators’ outlook for the next six months, stood at 101.2 in November, a decline of 0.2% compared with October.