When the city of Alexandria notified Carl W. Noller in May 1981 that his two-bedroom condominium was being assessed at $80,500, Noller did more than get angry.

He began a challenge of the city's methods of assessing condominiums, one of the fast-growing segments of the Northern Virginia real estate market. This morning that challenge will take the 38-year-old unemployed economist before the Alexandria City Council where he will call for an investigation of the real estate assessor's office and the man who heads it.

"I want the city to clean this mess up," said Noller. He said Alexandria's condominium assessment procedures are arbitrary, unfair and costly to numerous owners whose property values are inflated by the process.

Noller, who holds a doctorate in economics from the University of Virginia, blames the problem on David J. Chitlik, the city's director of assessments, who once was Noller's student in Charlottesville. "He is like the Mad Hatter," Noller said.

Chitlik, 32, says Noller is overly critical and calls him "an obsessed man who goes around like Paul Revere yelling: 'The assessor is coming . . . . ' "

Noller maintains that Chitlik cannot explain how five major condominium buildings were assessed last year. He said that when he uses Chitlik's own methodology, which basically uses recent sales in a building to gauge the value of its units, he finds the assessments are too high.

Noller also says Chitlik's methods frequently do not take into account differences among units in the same project. He cites Parkfairfax, a community off Shirley Highway, as an example. Noller says of the 106 units sold there in 1981, 88 sold above their assessed value, yet Chilik's procedure did not call for an increase in Parkfairfax's assessments last year.

Chitlik replies that Noller is expecting too much from an assessor's office. "This is not a statistically pure science," Chitlik said. "He doesn't or refuses to understand that much of the appraisal process is subjective. It has to come down to an assessor's judgment."

That's what troubles Noller. Chitlik, he says, has a tendency to ignore the results of his own methodology. By duplicating Chitlik's method, Noller says he discovered numerous examples of condominiums in which Chitlik improperly adjusted the assessments up or down.

Chitlik says his staff assesses condominiums by taking the sales prices of units in a project and comparing them to their last assessment. His office has developed a formula that computes the average change in the value of a sample of the project's units sold that year and then applies that percentage to all the units in the building.

The procedure is not always followed to the letter. Chitlik says that if his assessors notice sales patterns peculiar to certain types of units in a single building, such as those facing a highway selling for less than others, various classes of condos in a projects may be assessed separately.

Noller's protest had its origins in the spring of 1981 when his condo was assessed at $80,500. At the time, Noller says, none of the neighboring units was selling for that much. He appealed to the Board of Equalization, which reduced his assessment to $77,000. He also appealed his assessment last year, and won a reduction of $4,000.

Noller, a former economist with the U.S. Chamber of Commerce who works part time as a diet consultant, says his differences with Chitlik's office have nothing to do with his property. "I'm doing this because I want to see the city use an honest system," he says. CAPTION: Picture, Carl Noller was inspired to begin his challenge when his condominium unit was assessed at $80,500 by the Alexandria tax office. By James A. Parcell -- The Washington Post