BOSTON -- Barbara Anderson, director of Citizens for Limited Taxation, keeps a file of stories in which out-of-state reporters (including this one) have in her view misreported or misinterpreted the record of Massachusetts Gov. Michael S. Dukakis, a contender for the Democratic presidential nomination.

Anderson is hardly an unprejudiced source. She and her populist-conservative organization have pressured Dukakis and the Democratic legislature constantly and fought them often. But she is a smart, informed citizen-politician, and the specific factual errors and the glossy exaggerations she can point to in any number of national stories on Dukakis would not be dismissed out of hand by any sharp editor.

''I know enough to distrust much of what I've read about Dukakis,'' she said the other day. ''But it's made me wonder whether I can trust what they say about any of the other candidates.''

Anderson's comment highlights one of the main challenges facing the mass media of this country in the next 12 months. A year from now, the list of almost 20 men currently seeking the Republican and Democratic nominations for president will have been pared to two names. Today, almost all of those contenders are little-known to voters who will be making the critical choices in primaries and caucuses. The quality of the information voters get will directly determine the quality of those choices.

Anderson, for example, is attracted by what she's heard about Sen. Joseph R. Biden Jr., but she readily admits she hasn't heard that much. When Biden announces, I guarantee you that TV and print stories will all make the point that he has commuted home from the Senate to Wilmington almost every night in order to spend time with his children.

That's a fine habit but one of dubious relevance. The one thing we know about the presidency is that the office is in the house, so the willingness to commute to work is not a prime requirement. What Anderson and millions of others need to know is what Biden has done on the Judiciary and Foreign Relations committees that sheds light on the kind of president he would be -- or his readiness for the office.

They need to know what sort of House members Jack Kemp and Dick Gephardt have been, and what there may be in the ministries of Pat Robertson and Jesse Jackson that prepares them for leaping into public office at the top. But the same question applies to a former House member named George Bush, who has been ''a heartbeat away'' these past seven years. Just what exactly has he been doing since he became vice president?

Senate reporters for networks, leading newspapers and news magazines know quite a lot about the records and reputations of Biden, Bob Dole, Paul Laxalt, Al Gore and Paul Simon, just as reporters in Phoenix and Wilmington know a great deal about the work of former governors Bruce Babbitt and Pete du Pont.

But there is a reluctance to undertake serious appraisals of their work -- either because news organizations think viewers and readers would be bored or because journalists are nervous about saying what the people who know them best and have worked most closely with them think of the contenders. Either way, it's a cop-out.

A healthy example of the kind of reporting that's needed was provided here the other night at the Boston Garden. In the final minute of Game 5 of the Eastern Conference playoffs, two of the best players in the National Basketball Association faced off against each other.

Isiah Thomas, the Detroit Pistons' all-star, scored a difficult basket to give his team a one-point lead. The Boston Celtics came down the floor and got the ball to their all-star, Larry Bird, whose shot was blocked out of bounds, with Detroit awarded possession. Only five seconds remained, and Detroit's victory seemed ensured when Thomas threw the ball inbounds. But Bird suddenly materialized, stretched to intercept the pass and in the same fluid motion fed the ball to teammate Dennis Johnson, who scored the winning basket.

It was stunning -- but not unexpected. Years of television and print stories had led us to understand that while both Thomas and Bird were superb athletes, Bird played at a different ''level of the game,'' to borrow John McPhee's phrase about basketball-player-turned-politician Bill Bradley. The dumbest of us fans would have known enough to name Bird ahead of Thomas on a list of the most accomplished current players.

Well, politicians, like basketball players, play at different ''levels of the game,'' and voters need stories that help them understand that. Each of the presidential contenders has impressive credentials; each will have -- and deserves -- his own fan club. But the public needs to be able to discriminate the Birds from the Thomases -- and define the special gifts and shortcomings of each of them.

We're picking a president, and Barbara Anderson is not alone in wanting to know more about these strangers.