The desire of the American worker for jobs packaged in nontraditional sizes is demonstrated most dramatically by the growth of the country's "permanent part-time" work force.

Virtually nonexistent at the turn of the century, it now is the fastest growing segment of the work force and includes 16 million to 17 million people.

Most part-times are women, especially married women with children, and most of them (80 per cent) are working part-time because they prefer it to full time - not because they cannot find full-time jobs.

The bulk of part-time jobs are in the lower-paying "women's occupations" - retail sales and services, and clerical work.

It is in these fields that the number of part-time workers - who usually are on the job 18 to 20 hours each week - has increased the most, according to Stanley D. Dollen of Georgetown University. In the last 15 years, the number of part-time workers in these jobs has risen by 40 per cent to 50 per cent.

This rise has been accompanied by an increase in the temporary help industry which also includes mostly clerical and service jobs. Temporary workers are sent out by agencies, established for that purpose, to fill short term vacancies and may work an 8-hour day when employed. Part-time workers are employed on a permanent basis but for less than a standard work day or work week.

In 1946, there were only a few thousand temporary workers, according to Martin Gannon of the University of Maryland. Though data in this area are less reliable than most employment statistics, he says, estimates are that there are now between 1.6 million and 3 million temporaries employed in the nation.

Some temporary workers simply lack the skills to get full-time jobs, many others prefer to have less income and in some cases receive no fringe benefits at all rather than work full-time.

"The attitude toward temporaries is that they are people who can't keekp a permanent job. But we're not all turkeys," said Judy Lynn Lawson, 23, of Greenbelt, who is proud of her 104-work-per-minute typing speed. "A lot of us do it because it suits our life style best."

Gannon said a study of workers who did not work full-time showed that working mothers often had tried full-time work but then "reverted to regular part-time positions" as the best way to reconcile the conflicting demands of work and home.

There is growing pressure now to alter negative attitudes toward temporary and part-time workers so that they are considered for promotion and given a fair share of benefits. There also is pressure to expand part-time job opportunities into professional and managerial level jobs.

The Carter administration has taken some steps to expand part-time job opportunities in the U.S. government. One of the main deterrents, according to officials, is the federal personnel ceiling imposed by th Office of Management and Budget. Currently, employees are counted the same way whether they work two hours a week or 39, critics say.

OMB counters that the ceilings are necessary to check the growth of agencies, and that in many cases the ceilings allow for some part-time hiring but that many managers do not understand that.

Currently there are about 40,000 part-time federal employees (not including the Postal Service) or about 2 per cent of the total federal work force.

An advantageous combination of circumstances made it possible for economist Betty Barker, a GS-15 supervisory level professional at the Commerce Department to get the part-time schedule she wanted after she became a mother. There circumstances include the type of work she does, and the agency for which she does it.

Baker helps supervise 50 people in the Bureau of Economic Analysis and, she says, "My work involves not so much the day-to-day fire fighting, but is generally research and analysus, writing and editing papers, designing a survey...Other people in the office have been able to plan things around the days I'm in the office.

Supporters of expanded part-time and other flexible job opportunities argue that employers will find enough advantages to outweigh any extra costs, and improved morale and productivity among the employees.

For example, supervisors' working part-time in professional and technical positions at the Department of Health, Education and Welfare show that 55 per cent of them are more productive on a work-per-hour basis than full time workers.

In Boston, half-time public welfare caseworkers handled higher caseloads per hour than their full-time coworkers. They actually averaged 20 per cent more full-time workers. School administrators in several cities have maintained that their half-time teachers gave them two-thirds as much work for one-half as much pay.

While many temporary workers are housewives who want re-enter the full time job market eventually, increasingly are appealing to members of the mobile, freedom loving generation of younger workers, according to Barry Wright, of Temporaries, Inc.

"Washington is a typical example of a transient glamorous place to come and make your mark," he said. "In a situation like this, these young people use temporary employment as a way to get familiar with the local labor market. Some turn it in a life style and travel from city to city."