FARGO (AP) - The number of North Dakota high school students taking Advanced Placement tests to earn college credit has dropped slightly, and scores on those tests also are down.

Officials attribute the 1.6 percent decrease in participation to the rising popularity of the state's dual credit enrollment program, an alternative way of getting college credit while in high school.

Coursework leading up to those tests takes a semester, compared to the yearlong AP classes, said Michel Hillman, the state university system's vice chancellor for academic and student affairs.

"There has been a dramatic increase in dual credit enrollment," he said. "We're seeing more interest in dual credit than AP."

Nationwide, Advanced Placement test-taker numbers increased by 8 percent over the year.

The number of Advanced Placement scores that qualify test-takers for college credit dropped by about 14 percent in North Dakota, according to the College Board, the not-for-profit group that administers the tests.

"I was surprised to see that," Hillman said. "We can't really get our heads around why that might be at this point."