In the minds of most American voters, President Reagan was responsible for the current economic prosperity and was the candidate seen as more able to ensure that it will continue, according to ABC-Washington Post polls conducted on Election Day.

Perhaps the most notable economic change between the beginning of Reagan's term and now was one that was mentioned during this campaign only in passing: inflation. So far this year it has been running at around a 4 percent rate, far below its 1980 and early 1981 levels.

The price of reducing inflation turned out to be a massive recession in 1981 and 1982 that drove the unemployment rate up nearly to 11 percent. But the memories of that deep slump seemed to have been erased from the voters' minds. Or at least if it was not, they felt the game had been worth the candle.

No Reagan forecast ever showed a serious recession or any significant rise in unemployment, while still predicting a drop in inflation similar to the one that occurred. That alone raises questions about how much luck was involved in what happened, and in particular the timing of the early recession and later recovery.

In a speech yesterday before the American Stock Exchange, Undersecretary of Treasury Beryl Sprinkel maintained that the recovery "wasn't any fluke. It was planned." The president, he said, took a simple but sophisticated approach to reviving the economy, including spending cuts and support of the Federal Reserve's chosen course for monetary policy.

Sprinkel also reiterated a view expressed by White House Chief of Staff James A. Baker III and other senior administration officials that the major focus of economic policy in the new term will be spending cuts and tax reform, with continued efforts to reduce regulation of business.

There was little evidence in Tuesday's voting that the recent slowing of economic growth much affected voters' conviction that the economy is in good shape. The size of the federal budget deficit, a point often cited by Mondale as evidence that the Reagan economic program was in trouble, apparently was of less concern to voters than the level of government spending and the possibility of higher taxes. Reagan was seen as better able to hold down spending and less likely to raise taxes, according to the polling data.

To the now classic question of whether they were better off or worse off financially than four years ago, almost half the group of more than 10,000 voters polled said they were better off. Another 31 percent said they were about the same, while only 20 percent said they were worse off.

Their votes divided almost symetrically: only 15 percent of those who felt they were better off voted for Walter Mondale and 85 percent voted for Reagan; the numbers were almost precisely reversed for those who said they were worse off. The about-the-same group went for Mondale by a 56 percent margin.

In other words, it was the sheer size of the better-off group that dominated the results in this area. And those results mirror those of past elections. When incomes are rising strongly in real terms, incumbents almost always get reelected, and 1984 was no exception.

At the same time, the polling data indicate that the economic issue was not uppermost in voters' minds. Asked what was the one characteristic that best described the candidate they voted for, only 15 percent picked keeping the country prosperous. Of that group, four-fifths had voted for Reagan.

More of the voters, 22 percent, said that fairness to all groups described their candidate, and nine-tenths of those voted for Mondale.

But overwhelming both of those areas of concern or confidence was the combination of who would keep America strong and being a strong leader. More than 40 percent of the voters polled said that was the best way to describe their candidate, and out of that large group, well over 80 percent went for Reagan.

Asked what they most disliked about the man they did not vote for, some of those polled cited Social Security, unemployment and the federal budget deficit. Mondale carried nearly two-thirds of the voters who cited those issues but they collectively amounted to only 20 percent of the total.

The issue mentioned the most, in this negative sense, was tax increases. Republican advertising had hammered away on it after Mondale said he would raise taxes as part of his plan to reduce budget deficits. More than one-fourth of the voters said it was what they disliked most in the candidate they did not vote for, and more than 90 percent in this group voted for Reagan.

Another 21 percent of the voters said they most disliked the other candidate's stand on military spending. Just over 60 percent of that group went for Mondale. But that was largely offset by those disliking the other man's stand on overall federal spending, and from the voters mentioning that, Reagan got more than 80 percent of the ballots.

How Reagan will seek to use his new mandate to deal with the economic issues that were of concern to voters remains to be seen. With the president having promised not to cut Social Security benefits or reduce future cost-of-living adjustments to them, having more desire to increase rather than reduce military spending, and having no choice but to pay interest due on the rising national debt, administration officials will have an extremely difficult time coming up with an acceptable 1986 budget in January, according to most budget analysts.

Those programs alone account for about two-thirds of all federal spending. Moreover, most of the spending cuts enacted in the first Reagan term came out of the remaining one-third, and senior budget officials have said there is little appetite on Capitol Hill for major new reductions in programs that have already been cut back.

Meanwhile, the slower-than-forecast economic growth in the second half of this year is already taking a small toll in terms of federal revenue. Some private economists backing the administration continue to believe rapid economic growth will reduce future deficits. But projections from those economists last year that the red-ink figure would drop to a range of $150 billion to $160 billion turned out to be incorrect, with the fiscal 1984 total coming in at $175.4 billion.

Now forecasts for the current year, 1985, range upward to more than $200 billion, depending on how weak the forecaster expects the economy to be in the first three quarters of next year.