A headline in yesterday's Metro section should have said that violent incidents in Prince George's County schools have declined for the fourth consecutive year.

Security problems in Prince George's County public schools, ranging from alcohol possession to vandalism, fell 17.2 percent during the last school year and have been cut in half since 1981, according to officials.

In a study of school security released this week, officials reported declines since last year in the number of incidents of alcohol possession, which were down 46.3 percent; arson problems, down 41.2 percent, and vandalism incidents, down 37.6 percent.

The school system's Office of Security Services reported 2,666 incidents in the 1983-84 school year, compared to 3,220 incidents in 1982-83 and 5,519 in 1981-82.

Almost 60 percent of the reported problems involved crimes against property, such as arson, breaking and entering, and trespassing.

The study found that property damage to schools, chiefly from vandalism and arson, rose almost 59 percent to $553,843 last year, or $204,727 more than in 1982-83.

School officials attributed the decline in the number of incidents to increased emphasis by administrators on school discipline, including stringent expulsion rules adopted three years ago.

The rule requires the expulsion of students caught carrying weapons or distributing drugs, and those caught twice in possession of drugs.

"We hope that the rule has a residual effect" on other disciplinary problems, said school spokesman Brian J. Porter. "Discipline is the number one concern of parents and nonparents alike, and it behooves us to attempt to improve" students' behavior.

Despite the drop in the total number of incidents, the study reported a growing number of assaults on teachers, which rose from 66 in the 1982-83 school year to 72 last year, and an increase in the number of drug offenses, which were up from 251 in 1982-83 to 285 last year.

Assaults on teachers are "a prime concern" of Superintendent John A. Murphy, Porter said, adding, "He has heard from teachers and he believes there has to be a way to stop it."

Murphy, who is in his first year in the county post, has targeted discipline problems in his fiscal 1986 budget proposal.

The budget request, released last week, includes $546,000 for a countywide alternative high school that chronic troublemakers could attend for up to two years, and for suspension centers in each of the county's 20 high schools.

Among county high schools, Frederick Douglass High School in Upper Marlboro reported the largest number of problems per student, with 8.5 incidents per 100 students. High Point High School in Beltsville reported the lowest, at one incident per 100 students, compared to an average of four incidents per 100 high school students countywide.

Charles Carroll Middle School in New Carrollton topped the list of middle schools, with 13.9 incidents per 100 students, and Eugene Burroughs Middle Schoool in Accokeek had the best record, with 0.2 incidents per 100 students.

The average among the county's 28 middle schools was 3.7 incidents per 100 students.