The Republicans are supposed to be the party of parsimony in government and the Democrats the heavy spenders, but the budget history of the last 16 years tells a subtler story.

The last budget Lyndon B. Johnson sent to Congress was for fiscal 1970, when federal spending turned out to be $196.6 billion. Now Gerald R. Ford is recommending $440 billion for fiscal 1978, which would make an increase of 124 per cent for the last eight years of Republican rule in the White House, a compound annual rate of 10.5 per cent.

The increase in the eight preceding Kennedy-Johnson years, by contrast, was 84 per cent, a compound annual rate of 8 per cent.

Perhaps the first thing these full-term comparisons suggest is that our political sterotypes are overdrawn.

Presidents never have complete control over the budget, and certainly that was true of Richard M. Nixon and Ford.

To begin with, as they themselves so often pointed out in indignant budget and veto messages, Congress was in Democratic hands throughout their terms (though Congress was also Democratic in the Kennedy-Johnson years).

More important than the prevailing majorities in Congress were the prevailing trends in the economy. The main things that move the federal budget every year are not politicians, but the rates of inflation, economic growth and unemployment.

Spending in fiscal 1975 was fully $56.5 billion - 21 per cent - higher than in 1974. That was not the result of political decisions, at least not in any short-term sense. Inflation was especially high in 1973-74 - consumer prices rose 8.8 per cent in 1973 and 12.2 per cent the next year - and Social Security benefits have been tied by law to prices.

Social Security spending was thus $10.8 billion higher in fiscal 1975 than the year before without anyone having lifted a finger. SImilarly, the recession struck in earnest in the winter of 1974-75; unemployment shot up from 5.5 to 8 and eventually near 9 per cent; and unemployment insurance outlays increased $7.4 billion.

These things said, it is still instructive to see how the budget changed under the Nixon-Ford stewardship. The three main trends were growth, a shift in the mix of spending, and a corresponding shift in the mix of taxes.

Spending did rise $243.4 billion over the eight years, but most of that was simple inflation. Adjust for inflation, and spending went up only about 25 per cent. Adjust a second time for economic growth, and spending hardly increased at all.

Unemployment compensation is one of the few spending items that, while it rises in some years, also declines in others; it moves up and down with the unemployment rate. Take unemployment compensation outlays out of the spending total, since they merely mirror the business cycle; then take federal spending as a percentage of gross national product - government spending alongside total spending in the economy.

The budget adjusted this way was 20.1 per cent of GNP in fiscal 1970, and the budget Ford submitted yesterday would be 20.9 per cent of projected GNP in fiscal 1978.

That is an increase, to be sure, but hardly a revolution.

The budget is generally broken down into specific and familiar spending programs - Social Security, revenue sharing, weapons procurement and so on.

Economists sometimes find it useful to use a different, more general grouping of expenditures.

First come what they call transfer payments - various benefit payments directly to individuals. Then come grants to state and city governments and the net interest the federal government pays on its debt.

Everything that is left, except some monir bookkeeping items, is classified as federal purchases of good and services. This is the cost of running the federal government itself - the money it takes to pay the government's civilian and military employes, plus the cost of all the things from tanks to pencils that the government buys. These purchases of goods and services are in turn divided into defense and non-defense, which means the Pentagon and the rest of the government.

In the fiscal 1970 budget, the last one Johnson sent to Congress, defense purchases of goods and services were 38.4 per cent of total spending, transfer payments 29.1 per cent and grants to state and local governments 11.6 per cent.

In the recommended 1978 budget defense outlays have fallen to 23.6 per cent, transfer payments have risen to 40 per cent, and grants to state and local governments have edged up to 15.6 per cent.

The checks the government sends out each month to individual citizens and state and local governments are up; defense spending, as a percentage of the budget, is down.

Until fiscal 1976, defense spending had also been dropping each year in real terms, after adjustment for inflation. This was partly due to the winding down of the war in Vietnam. LIke Nixon before him, Ford resisted this trend, and in the current fiscal year, 1977, real defense spending has turned up.

As to transfer payments, fully half the dollar increase over the Nixon-Ford years has come in just one program, Social Security, which by itself now makes up about a fifth of the total budget, and nearly two-thirds has come from Social Security and Medicare together.

These two giant programs that have come to dominate the budget - Social Security now goes each month to one out of every seven Americans - have two common characteristics. The first is that both are "indexed" to inflation, Social Security formally, Medicare implicitly, so that outlays rise automatically each year with prices. It is in this sense that the budget in "uncontrollable."

The second characteristic is the way they both are financed - through the Social Security tax, which includes the money for Medicare as well as Social Security itself. And this leads to the third budget trend of the last eight years: The tax mix.

The individual income tax is progressive; the higher a person's income, the higher rate that person has to pay.

The flat-rate Social Security tax has the opposite effect. It is regressive, in that it bears relatively harder on those with low incomes than those with high ones.

As Social Security and Medicare have risen in importance on the spending side of the budget, so the Social Security tax has risen on the receipts side - and the total federal tax structure has become less progressive in the process.

In fiscal 1970 the individual income tax accounted for 48 per cent of federal tax receipts, the corporate income tax 16.9 per cent, and "social insurance contributions," meaning mainly the Social Security tax, 25.2 per cent, with the rest from minor sources.

As projected for fiscal 1978, the individual income tax will be down to 43.8 per cent, the corporate income tas to 16.1 per cent - and "social insurance contributions" will have risen to 33.7 per cent. They will be up from a fourth of the total to a third.

To some extent the two sides of the federal budget - tax and spending - have thus been working in opposite ways in 1970s.

Transfer or benefit payments tend to go mainly toward the lower end of the income spectrum. Thus on the spending side, for all the clamor over the spending of assorted programs for the poor from Lyndon Johnson's Great Society days, the budget has become what might, for shorthand purposes, be called more "liberal."

On the tax side, however, the opposite has been true. A major problem of the incoming Carter administration will be how to cope with this split - how in the future to finance Social Security and Medicare together with the rest of the benefit sector of the budget. CAPTION: Picture 1, WHERE IT COMES FROM, Individual Income Taxes $171.2 billion 39%; Picture 2, Social Security, Other Payroll Taxes $126.1 billion 29%; Picture 3, Corporation Income Taxes $58.9 billion 13%; Picture 4, Borrowing $47 billion 11%; Picture 5, Excise Taxes (Cigarettes, Liquor, etc.) 4% $18.5 billion; Picture 6, Miscellaneous $18.3 billion 4%, The Washington Post