Liz Lerman, who appeared with her Dance Exchange Performance Company at the Marvin Theatre last night in a program labeled "Docudance," is such a live wire you never know where the sparks will fly next.

She's made dances about baseball, cancer, our endangered ecology, the forgotten menials of the work force, types of people who visit art galleries, and about God, among other things. She's organized and directed an ongoing dance company of senior citizens, called the Dancers of the Third Age. She's a dancer, a choreographer, a teacher, a community activist and a born leader.

It's hard to know where her center is, because it's never still. Her gift for comedy, both physical and verbal, hints that at heart she's a vaudevillian. But then her proselytizing zeal--dance for all, by all, of all--suggests that she's fundamentally an evangelist. And then again, there's her espousal of causes, her urge to save the world--maybe "crusader" is closer to the mark.

One consequence of these wildly diversified activities and interests has been erratic swings in the quality of what she produces, and last night's program wasn't an exception--some things seemed sophomoric and slapdash, others brilliant and polished. A major thread in her work of recent years has been making dances about specific contemporary social and political issues. "Docudance" was a both a summation and an extension of her efforts in this direction, consisting of four dances dating from 1980 to the present, and ranging in subject matter from political art, the economy, and military policy to video games. The evening as a whole was like a shallow parabolic arc--it started up high, gradually dipped low, then swooped up again for the finish.

The first three parts of "Docudance" are roughly in the same mold, and heavily dependent on words--they are as close to theater as they are to dance, and in some ways closer. That's fine, but as the trio progresses, the validity of the movement aspect and the verbal inspiration begin to seem more and more tenuous.

By far the most effectively sustained part is the earliest, titled "Hostages, Whales and Artists," in which Lerman plays herself, a choreographer, and the other dancers represent caricatures of American family figures--on the whole it's the driest and funniest portion of "Docudance," and the most telling in its coordination of dance and language. One family daughter, for instance, given to martyred poses and gestures, is "a concerned citizen--she's taken herself hostage until the Americans are freed in Iran, and she's got a yellow-ribbon collection." Throughout the piece, Lerman not only handles the issues with a light touch, but questions her own artistic methodology in a humorous and insightful way.

The second part, "Reaganomics," which caught the national spotlight last year with its quotations from budget director David Stockman, seems much less consistent in retrospect, exploiting its own topicality without enriching it choreographically.

Though the new third part, "Nine Short Pieces About the Defense Budget and Other Military Matters"--performed solo by Lerman--has remarkable, ingeniously histrionic patches, on the whole it seems like simplistic polemics illustrated by uneven charades.

The real surprise was the fourth part, also a premiere. "Video Arcane," for nine dancers, makes its arresting points, for the most part, without words--suddenly Lerman the choreographer reasserts herself over Lerman the sermonizer, with very interesting results. Accompanied by electronic music and visuals, the piece depicts a society of video arcade addicts who acquire all the robotic, spidery, tic-like traits of the pac-persons they're obsessed with--you can hardly tell the players from the game. The wonder is that Lerman not only captures the puerility of videomania, but its hypnotic fascinations as well.

The program will be repeated today in both a matinee and evening performance.