Federal Reserve Chairman Kevin Warsh has said that “trends matter most.” Wednesday’s quarter-point rate increase tests that standard. What trend tipped the decision now? August consumer inflation was 3.4% overall, while inflation excluding food and energy was 2.4%. Energy rose 16.3% over the year, and gasoline 27.4%. Gasoline alone produced more than one-third of the monthly consumer price index increase. That is a real problem, but a snapshot does not explain the policy choice.

The direction of travel is more revealing. Monthly headline inflation accelerated to 0.4% from 0.1%, largely because of energy, while annual core CPI eased from 2.5% to 2.4%. Supercore inflation is not one fixed official measure. The Bureau of Labor Statistics reported services excluding rent of shelter up 3.1% over the year, while all items excluding food, shelter, and energy rose 2.0%. Both increased 0.3% in August. This is an energy rebound layered over moderating core inflation and sticky services. It supports vigilance but does not make a rate increase self-explanatory.