The unsung stalwart of the nation's economy - the small business sector - is getting some long overdue attention from Congress, which is wrestling with the problem of how to take that sector's pulse without overburdening small businesses with paperwork.

Fortunately, most of the information the government needs to track the small business sector is already in the hands of one federal agency or an other, according to a Census Bureau official.

Testifying yesterday at joint hearings sponsored by two Senate subcommittes on the "Small Business Economic Policy and Advocacy Reorganization Act of 1977." Shirley Kallek, the bureau's Associate Director for Economic Fields, said:

"There is a signifivant amount of information in basic surveys and in the administrative records of government agenices which could be used much more extensively" in building a small business data base.

Kallek eited Census Bureau statistics which showed that 62.7 per cent of all people employed in the United States are employed by companies with less than 250 employees. More than half of the companies in the U.S. have no employees other than the owner, she testified.

Kallek stressed the importance of administration's awareness of "the economic status of the small and medium-sized business sector," and called for data to put together in a clear and understandable form.

Such data is important, she said, because "it gives us the opportunity to see the relationship between small business and big business," and helps guage the reaction of small business to government actions and economic conditions.

Mary T. Mitchell, Assistant Director of the Division of Bank Supervision for the Federal Deposit Insurance CorP. followed Kallek's testimony with a call for a better understanding of information gathering.

The proposed legislation seeks to break down business loans into several categories, including loan applications that have been rejected.

Mitchell defended small bankers who are complaining that they cannot provide the information with case.

"There would be a significant burden on many small banks, if they are asked to provide some of this information," she said.

"Any bank participating in this survey will have a substantial compliance cost," she said. She added that most small banks don't keep records of loan rejections, because "many don't even reach the paper stage."

"We're glad to see someone project the banks," said Sen. Thomas J. Mclntyre (D.N.H.) who chaired the hearing. "A lot of them ought to be paid for this information."

The final witness, Milton Stewart, chairman of the Rescarch Council for Small Business and the Professions, said the Small Business Administration should provide the leadership in developing new economic indicators of the small business sector.

"We need to know if the small business sector is growing as rapidly as big business," setwart said, "and to know what policies have effects on small business."