Home sales are holding steady, with slight increases reported in some areas of the country, easing earlier fears that the October stock market collapse would cause many Americans to cancel sales contracts or decide not to buy houses at all, the National Association of Home Builders says.

Lower mortgage interest rates resulting from the market's plunge kept sales up, indicating that rates were a more important factor than stock market behavior in decisions to buy a house, said Kent W. Colton, NAHB's executive vice president. The association also said that buying a house "is still the best and safest investment" for most U.S. households.

Other analysts believe, however, that many people are uncertain about the future of the economy and will be hesitant to buy houses and make other major purchases.

Although the "vast majority" of Americans were not hurt by the stock market crash, they "are more cautious because they're worried about the overall economy" and the possibility of a slowdown in growth, said Kenneth T. Rosen, manager for real estate research at Salomon Brothers Inc. When people are uncertain about the direction the economy will take, they decide to stay where they are, he said.

"Volatility in the financial markets remains incredibly high ... and this has made it more difficult for either lenders or home buyers to feel comfortable that today's rates will last for long," the Federal National Mortgage Association said in its most recent economic forecast.

The Washington metropolitan area is one of the busiest housing markets in the nation, and is expected to remain strong. Housing is "a historically good investment" in the Washington area and will be more attractive because of the October drop, predicted David E. Strachan, executive director of the D.C. Association of Realtors. Sales are not dropping, and in fact may be increasing slightly, he said.

The number of building permits issued in Washington for single- and multifamily units, the gauge for measuring housing construction, rose by 4.3 percent in the first nine months of this year over the same period in 1986, with most of the increase coming in the number of apartments, according to Commerce Department figures compiled by Regis J. Sheehan & Associates, a local economic consulting firm. The region ranked sixth last year among 20 major metropolitan areas, with 39,098 permits issued.

NAHB officials said their predictions for the national housing market in 1988 were more pessimistic before the October market drop, primarily because interest rates were rising. Fixed-rate home mortgages had topped 12 percent and appeared to be headed for 13 percent, a level that would be "devastating" for housing sales, Colton said.

Since Oct. 19, the rates have declined by about a point, to between 10.5 and 11 percent, bringing a home purchase within the economic reach of more people. As a result, builders are reporting small increases in single-family home sales nationwide and say more shoppers are visiting model homes, the NAHB said.

David F. Seiders, chief economist for the home builders' organization, said rates are expected to go up again by the end of next year to about 12 percent, one point lower than they would have been had the stock market collapse not occurred. Early in 1987, interest rates fell to slightly below 9 percent, then bounced up and down during much of the year and were above 12 percent in early October until the market collapse helped bring them down again.

Seiders said home builders at first feared that many buyers would cancel purchases that were in progress after the market decline, but few did.

Construction was started on fewer homes in October than in any month since April 1983, at a seasonally adjusted annual rate of 1.5 million houses. The decrease was expected because of the increase in mortgage rates, Seiders said.

Despite that setback, the NAHB predicts that 1987 overall will prove to be a good year for the industry, with a total of 1.63 million housing starts by the end of this month.

Indications of slower economic growth by the middle of next year already were emerging before the stock market's troubles. The weakened economy and changing population patterns are expected to reduce housing starts to 1.48 million in 1988, Seiders said.

Many analysts agree with that prediction, citing a variety of reasons. "A lot of housing has been produced in the last few years," filling much of the backlog in demand, said Anthony Downs, an economist at the Brookings Institution.

But Downs said he is optimistic about the future. "A lot of people think there will be a recession. I'm not one of them," he said.

Several analysts emphasized that it is still too early to make accurate predictions about the real estate market. "A big cinder block was thrown into the economic pool and it landed in New York. We have no handle on how deep and how far the ripples will go," said George Sternlieb, a Rutgers University urban policy expert.