In my long-awaited memoirs, tentatively titled "Confessions of a Santa Claus Critic: The Pitfalls of Charismatic Differentiation Among the Seasonally Employed," I will bury the notion that rating Santas is a highly subjective, arbitrary and quixotic process, and spell out how computers have turned the ancient art of Santa-rating into an exact science.

Disguised as a mother and three children, we wait on the lines, buy the pictures and accept the coloring books. Then we caucus in the car.

The Credibility and Charisma factors are paramount. Bobby pins in the hair, ill-fitting beards and obvious youth, for example, are negative credibility factors. For charismatic evaluation I rely heavily on my highly experienced assistants: Tabitha, nine, and Caroline, six, veterans of six seasons of evaluating Santas. To offset any lack of spontaneity, there's Charlotte, new this year and a true tabula rasa as far as Santa Claus is concerned. Any Santa whose lap Charlotte will not immediately squirm out of gets bonus charisma points.

Then there are affirmative-action points for black and/or female Santas. We encountered none of these this year, but our data base is too narrow to call this a trend.

Finally, this is all corrected by the Writer Irritability factor, which upgrades the rating by the square root of the number of times I have to circle the mall looking for a parking place.

Here's what the computer spat out this time around: WOODWARD & LOTHROP, F Street store: The smell of baking gingerbread, the piped- in Nutcracker music and the selling floor piled with toys scored high on the Christmas ambiance scale. So did the Santa setting, a little red farmhouse with hex signs in a snowflake motif and manchichi monkeys on the roof. Santa himself -- the one who was there last Saturday at noon -- was an affable young man, who got a few negative credibility points for some dark hair showing through the white hair-and-eyebrow makeup that didn't withstand scrutiny. Though he didn't lose points for coming on too strong -- as some Santas do -- he was a bit too laid-back for a high charisma score. "He just wasn't Santa Claus," Tabitha said, as soon as we were out of earshot. "When I asked him for Master Merlin, he said he'd seen those in stores. "But Santa Claus is supposed to make his toys." Picky, picky. But what it boils down to is an acceptable but unmemorable Santa Claus, forgotten as soon as my staff disappeared into Santa's kitchen to decorate gingerbread people made by friendly elves. Computer readout for this Santa, out of a possible 10 score, 6.0000. PRINCE GEORGE'S PLAZA, Hyattsville: If you can ignore the fact that just a few feet away someone is hawking letters from Santa for money, this Santa has a pleasant setting in a garlanded white gazebo surrounded by Christmas trees. Santa himself was out feeding his reindeer when we arrived about 2:30 Saturday afternoon, but he soon reappeared to greet the waiting throng with a wide smile that conjured up visions of Barbie swimming pools and Dukes of Hazzard racing cars. A genuinely older man, he had a classic Saturday Evening Post Santa Claus face: twinkling blue eyes, faintly hawkish nose, good teeth. He was also well made-up: just the right amount of rouge and tufts of cotton for eyebrows. More important, he seemed to like children: He asked their names and remembered them. He let the shy children whisper in his ear and seemed to know instinctively when to talk softly. Charlotte slept through this one, but my other assistants graded him tops. Said Caroline, "I liked him a lot more than the first one because he was more like Santa." Added Tabitha, "He was more natural." Only one factor detracted from Santa's score from an adult point of view. After my assistants had reeled off a list that would have made any less-generous Santa's head swim, this one said: "That's easy. I'll be sure and get you those." The computer, taking into account the Credibility Risk Due to Unrealized Expectations, rated this Santa 9.9999. LANDOVER MALL: The theme here is Sesame Street, with Big Bird, Grover and the Gang in garish Technicolor outfits and Santa sitting in the corner-candystore set on a Wizard of Oz-like platform in the middle of a large fountain pool. Santa -- at least the Santa on duty last Saturday afternoon about 4 -- didn't quite have enough charisma not to be dwarfed by this rather grandiose setting. He looked like a right jolly young elf, with nice granny glasses, but he had a complexion a bit too sallow for true Santa-ness. My assistants liked him, however, and Charlotte sat on his lap just long enough for a quick photo. The fact that there's a toy train to ride on for 35 cents while a parent waits in line also helped boost this Santa's score. Final computer reading: 8.9999. IVERSON MALL, Marlow Heights: Iverson has changed its Santa setting from a Jellystone Bear theme to a candy-store motif, but when we arrived at 6 on Saturday we saw the same Santa who's been playing to rave reviews and packed houses at this mall for several seasons. He's an elderly gentleman with clear blue eyes, a generous nose and a kindly manner. He also has very protective elves who insisted that he take his break as scheduled. "It's very hot in there, ma'am," the head elf explained, indicating the candy store. Santa did indeed look weary, a very appropriate look for a Santa this time of year, and we can only laud the elves' protective instincts. The computer, using the partial data gathered this year and the more complete data gathered on previous visits, gave him a 10. GEORGETOWN PARK: We had to return to Georgetown Park not only to see the beautiful Victorian decorations but also to see whether last year's Santa -- a nice, sandy- haired young man who had neglected to tuck white hair into the back of his Santa cap -- had returned and, if so, had he grown some white hair? But the Santa we encountered at 1 on Sunday was a different young man, with white appropriately covering the back of his neck. A sprig of holly on his hat gave this Santa a rakish look we found rather appealling, but his rouge had been applied heavily and indiscriminately. This negative credibility factor was partially offset by his jolly manner and by the fact that part of the photo fee goes to UNICEF, earning him points through the Peace-on-Earth- Good-Will-to-Persons factor. Our computer rated him 7.9999. LANDMARK SHOPPING CENTER, Alexandria: Any Santa who plays Landmark this year has a lot to overcome, and the Santa we found there last Sunday afternoon lacked the wherewithal. Landmark has relegated Santa to an obscure corner of its underground and seated him in a ticky-tacky green-and-white throne. Santa, when we finally found him, was pleasant but pallid. A little rouge would have brightened his pasty cheeks, but the cure for his weary manner, unseemly in an obviously young Santa, might be more elusive. He did win some adult approval points, however, from the perspicacity of his questioning. "Do you ever fight with your sister? Do you keep your room clean?'' he asked. He was also kind enough to pretend to believe the answers. Our computer digested this data and gave him a 5.999. SPRINGFIELD MALL: Springfield, which also has Rudy the Talking Reindeer and walking gingerbread cookies, has a Santa with a bit of stage business that made us program a whole new factor into our computer. He had developed a very convincing belly shake -- at least the Santa on duty last Sunday at 4 has a very convincing belly shake. At intervals he stands up, puts his thumbs in his belt and makes his belly shake like a bowl full of cherry jelly, just as Clement Moore described it. The belly shake was a real plus, as was his friendly manner and the fact that Charlotte sat on his lap, although she paid more attention to a giant mechanical marionette overhead. There were negative factors that brought down the final score, however: A better makeup job would have drawn attention from his eyes which, though twinkling, were a bit on the beady side for a classic Santa. The computer chewed all this over and spat out a core of 8.999.