FOOTBALL'S HOME-FIELD advantage applies as well to elections. Candidates, especially presidential candidates, are expected to run better in their home precincts among the home folks. If the people who know the candidate best do not support his candidacy, the reasoning goes, then how can any candidate ask people who do not know him for their votes?

Of course, this thesis conveniently overlooks the fact that Franklin Roosevelt was never very popular in Hyde Park and that John Kennedy's Hyannisport neighbors deprived him of any landslides. But still the standard is with us. Sen. Edward Kennedy won the Massachusetts primary two weeks ago, quite handily, but not nearly so handily as President Carter won the Georgia primary one week later.

This past Tuesday, Rep. John Anderson ran a respectable second in his home-state primary in Illinois. But because it was his home state, the defeat probably hurt Mr. Anderson and his chances more than if he had finished second in California, which is, of course, the adopted home state of former governor Ronald Reagan, who is a real-live native of Illinois -- which he won.

Mr. Reagan's dual home-state citizenship, however, is as nothing to the problems confronting George Bush in the next few weeks. For Mr. Bush, as proof of the mobility of our population, is a true victim of the multiple home-state syndrome. He has three -- count 'em, three -- home states he needs to win. Mr. Bush was born in Massachusetts, and he capitalized on that fact in winning the Massachusetts primary. But he grew up and went to school in Connecticut, which gives him a second home state. Connecticut is holding its primary next Tuesday, and Mr. Bush will be expected to do well among those voters "who know him best."

If Mr. Bush had only remained in Connecticut, then next Tuesday would be the end of these extravagant expectations. But as a young man, he moved to Texas, where he founded a business and was elected to Congress. So George Bush has three home states. That's too many. It imposes a cruel and unusual burden on a candidate.We think that there should be a law declaring that a presidential candidate can pick any two states he has lived in as his home states and that nobody should have to be a favorite son anymore. How did the reformers, who have done so much to perfect our system, happen to overlook that one?