Believe it, or not? That's the question of the day in Argentina, where economic stability may depend on the credibility of a new inflation index.

Critics say that Argentina has been systematically underestimating inflation and thus overestimating economic growth. Even many government allies distrust the official numbers.

The government promises to solve the problem Thursday by introducing a new index developed with help from the International Monetary Fund.

The old index almost always reported monthly inflation at less 1 percent, when any shopper could see their costs growing much higher. Private economists told Congress that January's inflation was 4.6 percent — the highest in many years.

Economist Matias Carugati says that no one will believe the new figures if they show less than 3 percent inflation for January.