VIEWED FROM the perspective of most families' checkbooks and dining room tables, the national economy has been on a dispiriting plateau since the early 1970s. Inflation seems to devour the gains in income immediately. In everything touching wealth and money, most Americans consider the country to be stagnating. But, curiously, the figures show a different pattern.

The statistics, in their neat rows, reflect an economy that has recovered strongly from the last recession and has carried most Americans with it. Personal income, per capita, after taxes and after inflation, has risen-not spectacularly, but steadily. Purchasing power in the hands of consumers is up.

This collision of perceptions, the typical family's versus the statistician's, is one of the perplexities of current American politics. Every American administration for a generation has embraced the responsibility to sustain economic growth. But currently President Carter and Congress are competing to slow the pace of growth by balancing the federal budget - although they probably face a recession later this year, and they certainly face a election next year. Growth, they accurately say, has reached a dangerously inflationary point. But if growth has been strong, why do so many Americans feel pinched?

While real incomes per capita for the whole population are up, it's mainly because a larger proportion of the country's population is now working than ever before. If a family has the same number of jobholders, doing the same kinds of work as in the early 1970s, it is indeed likely to have a little less real income today that it did then. But in other families, wives and children have taken jobs and that's what mainly accounts for the rise in the averages. Since 1973, the number of working women has increased by 7 million, almost twice the increase in working men.

Expectations are important in accounting for changes in public moods, and the past six years have been a time in which expectations about money have been generally unfulfilled. The great boom of the 1960s ran on with a couple of brief lapses, through 1973. People had organized their lives and finances on the assumption that the accustomed raises in income would continue. They didn't, and that has left people feeling strapped even when they have suffered no actual losses.

Perhaps that's why there's endless talk now of austerity and retrenchment event though, collectively, the country is still getting wealthier. Individually, wage earners are making about what they did six years ago, or perhaps a little less. The American standard of living continues to rise. But currently it seems to be due chiefly to the working wives.