On a monthly basis, the core index rose 0.2 percent in October.

Even excluding energy costs, prices increased more than expected, with the core index rising 0.3 percent.

Excluding energy, the so-called core index rose a scant 0.1 percent, the same as in May.

The so-called core index, which excludes volatile food and energy prices, rose 0.7 percent.

The core index, which excluded the volatile food and energy sectors, was unchanged.

Excluding food and energy, however, the core index rose a greater-than-expected 0.6 percent.

But the increase last month in the core index was misleading, analysts said.

Economists had forecast a 0.2 percent increase in the core index for September.

The core optical index of refraction is also subject to variations.

Last year, this core index rose 2.3 percent from 1997.