The producer price index showed that the core finished goods index jumped 1.3 percent in November, more than reversing a 0.9 percent decline reported for October. Much of the story was passenger cars and light trucks. They rose by 2.2 percent and 13.7 percent, respectively after showing October declines of 2.3 percent and 9.7 percent. This reflects the timing of discounts, which was an important factor holding down the November CPI. The moral of this story is that price data (like most data) are very erratic. You can never make too much of a single month's data. If the data look very different from prior months' data, then the odds are that it is an aberation which will be reversed in future months.
--Dean Baker