In the wake of Mayor Marion Barry's arrest, far too many pundits have drawn political conclusions about the District based on sloppy assertions regarding the size and nature of the D.C. government work force. The latest was Mary McGrory {June 7}, who asserted that one out of every three households was somehow directly dependent on the mayor for a paycheck.

A phone call to the D.C. Office of Personnel confirmed that as of Dec. 30, 1989, the District employed 48,195 persons, of whom only 27,712 live in the city. The District has approximately 257,000 households, so even with the widest job distribution of one worker per household, the proportion of the D.C. work force to the number of households would be one-ninth, not one-third.

Further, nearly all D.C. employees are covered by civil service regulations modeled on those of the federal government, union contracts with third-party grievance procedures and/or Hatch Act restrictions. Of course, all may avail themselves of the secret ballot too. Approximately 17,000 work for agencies with independent personnel authority excluded from the mayor's purview, such as the D.C. public schools, the University of the District of Columbia and the courts.

Clearly, an organized public work force can have, and is entitled to have, a political impact, but an analysis of that impact ought to rest on at least a little research, not on hand-me-down suppositions that, unfortunately, pass into the folklore. SUZANNE CROWELL Washington