Is there anything more annoying than buying toys that the kids won't play with? This is a problem that gets more serious as the years go by - from dolls to bicycles to computers to cars.

And this is a dilemma for toy companies too, who hire people such as toy consultant Ruth Rolfberg to figure out what kids want. Her studies are geared more toward the boardroom than the living room, but the findings are worth noting. Here are some basic rules:-Buy toys kids can learn from, but make sure they have no similarity in any way to homework. That works for geography and some word games, but scientific experiment-type toys are out.

-Buy toys that the kids can figure out how to use without reading the directions. And if they have to read the rules, make sure they are simple.

-Kids think games that involve a lot of rules (simple or not) or concentration are a bummer.

-Most often, boys and girls like the same toys.

Rolfberg did her most recent study last month for the Christmas buying season and had 352 5- to 9-year-olds playing for about 1,700 hours with 19 different toys. So each toy gets an hour-a-day workout from each kid for about a week. Not bad! If I could get my 31/2-year-old to play with something for a week, I would consider that toy to be a major success.

The top toy for all around "playability" was the Fisher Price "PXL 2000 Camcorder." It was followed by Fisher Price's Star Stage, Remco's "Footnotes," Hasbro's "Body Rap," Milton Bradley's "Bed Bugs," Fisher Price's "Discovery Globe," Milton Bradley's "Guess Who?," Fisher Price's "Magic Scan," Western Publishing's "Shrieks & Creaks" and Hasbro's "Road Hogs."

The lowest-rated toys were science project kits and strategy board games.

Playability, of course, is not the only criterion you should look for; safety is the other. Dangerous toys abound on the market and you must be ready to screen them yourself.