The accuracy of a year-old survey that shows that almost one out of every 20 low-rent apartment units in the city stands empty was attacked yesterday by community leaders.

The survey, which the community leaders fear could be cited as the basis for allowing thousands of low-rent apartment complexes to be coverted to condominiums, shows a vacancy rate of 4.88 among those apartments were a one bedroom unit rents for $215.50 a month or less.

According to the D. C. Condominium Act, such apartment complexes could be converted to condominiums if the vacancy rate is determined by the mayor to exceed 3 percent.

At a hearing yesterday at the Department of Housing and Community Development's main office, Bill Washburn, a spokesman for the Coalition for Community Reinvestment, testified that the COG survey represents the results of a "hastily drafted law and a hastily done survey." The Coalition for Community Reinvestment is an umbrella organization representing 20 groups.

"It frightens us to think that, based on this type of research, policy directives for the housing stock and housing opportunities available to low- and moderate-income families may be restricted," Washburn said. He said he fears that, if allowed to convert, many apartment owners with low-rent units will do so gladly.

Speakers yesterday criticized the COG study, which was prepared by the Metropolitan Washington Council of Governments with the help of the Municipal Planning Office on several grounds. They said that it was conducted entirely by mail and that the response rate was low, that there was no requirement that units surveyed be habitable, that there was no consideration of apartment turnover rates in the city, that it didn't consider the issue of overcrowding, and that it excluded buildings with less than three apartments.

Several speakers also said the survey was biased because the respondents - property and resident managers - had an interest in the outcome of the survey.

"They could have filled out the study and exaggerated the vacancy rte," said Tim Siegel of the City-Wide Housing Coalition. "The landlords were told the outcome of the survey would effect how the mayor and the City Council look at it.It is so prejudiced."

In addition, Hank Leland of the community reinvestment coalition said that a 4.88 percent vacancy rate is considered low in central cities. Leland suggested that a rate of 5 per cent should be considered low, 6 per cent normal, and 7 per cent or above high.

W. Bruce Steele, COG's chief of housing programs, said after the hearing that some of the criticism made "by those more thoughtful and technically qualified" speakers were valid.

"For an important administrative decision related toa policy issue, the survey could very well be attacked on grounds of methodological inaccuracies . . . . The survey is very weak. We did the best we could with the limited time frame and the limited budgetary resources," Steele said.

Steele agreed that the city vacancy rate of 4.1 percent for all units is low for central cities on the East Coast. By putting a 3 percent threshold in the Condominium Act, the City Council set a standard for "an exceptionally low vacancy rate," he said, adding that the vacancy rate probably had not been that low in Washington in "15 or 20 years."

Roy Priest, chief of the city housing department's planning office, conducted the hearing and said he will make public his assessment of the survey's accuracy in time for the community to make further comments before a recommendation is given to the mayor. He said the testimony yesterday was "substantive." He added that part of the problem may have been that not enough details about the COG survey were outlined in the summary of the survey that was made public.

One speaker representing a survey research organization said at the hearing that a more adequate survey of the city's vacancy rates could be conducted over a six-month to nine-month period and could cost roughly $200,000 to $250,000.

The only speaker who testified in favor of the COG survey was John T. O'Neill of the Apartment and Office Building Association.

O'Neill, who said the survey was "statistically sound," also said, however, that it should have taken into account the city's high apartment turnover rate and the fact that many owners have units that technically are not occupied at a given time but may have a tenant already chosen who is about to move in.

O'Neill said about other testimony opposing the COG survey, "Nobody likes the results of the survey because it means a landlord could convert without a tenant vote. I don't think the vacancy rate citywide has ever been lower than 3 per cent."