Inflation blipped up in November, the government's statisticians say. It isn't very serious, so far. The blip was not a large one. But it draws attention to the narrowing choices available to the people who make American economic policy -- which currently means the Federal Reserve Board -- as the exchange rate of the dollar falls.

When the dollar falls, imports cost more -- and not only imports. Foreign competition holds down the prices of a lot of domestic products -- automobiles, to take a prominent example. When prices of imports rise, that allows American producers to raise their own prices as well. For some time this country has had, in terms of inflation, a split-level economy. Inflation has been low among all the things that are traded internationally -- food, clothing, cars and fuel being he most important. But among those things not affected by foreign trade, the inflation rate has been startlingly high. Prices of houses have risen nearly 6 percent over the past year, and rent has been going up even faster. Medical care is up 6.6 percent. College and school tuitions are up 8 percent. The average for all consumer prices rose only 3.6 percent in the year ending in November, but cheap imports have been holding that average down. As imports become less cheap, the inflation rate is going to rise.

That leads to an interesting political question: how much inflation is the country prepared to tolerate to keep unemployment from rising further? Not much more, by all the present indications. The question will ultimately have to be answered by the Federal Reserve Board. To control the economy the government has two principle levers, federal spending and interest rates. Spending levels are now going to be determined automatically by the Gramm-Rudman-Hollings legislation. That leaves interest rates, which are the responsibility of the Federal Reserve Board. The Gramm-Rudman-Hollings requirements, enforcing declining deficits, will slow the economy down unless they are offset by falling interest rates. The Federal Reserve evidently feels that it can keep nudging interest lower as long as the inflation rate remains low and stable, as it had done this year. But if the rise in consumer prices goes over 5 percent a year, the yellow lights are going to be flashing. Under those circumstances the Federal Reserve might well decide that it could not let interest rates decline any farther.

A lower exchange rate is crucial, to push this country's trade toward balance and end the present dangerous accumulation of foreign debts. But the sinking dollar has important consequences for the economy here at home. It's probably still possible to get through the coming year with moderate but continuing expansion of the economy and no significant change in unemployment. But it will take steady nerves at the Federal Reserve, as well as the usual ration of good luck.