Utah again exceeded national averages in ACT college entrance test scores, according to results released today.

Yet achievement gaps between whites and ethnic minorities for the Class of 2006 test-takers continue — even when some ethnic groups report higher percentages than whites enrolled in rigorous courses.

Why?

There is no easy answer. Education experts caution against drawing conclusions with insufficient data, a single test or using small samples. Still, the information adds to complex data on achievement gaps, an issue being debated locally and nationally.

"The problem is very tenacious and very complex," said Patrick Galvin, Salt Lake District research, assessment and evaluation director. "We've not found a silver bullet to fix it."

Utah's average ACT composite score rose from 21.5 to 21.7 between 2005 and 2006, surpassing the national average of 21.1, which was up from 20.9.

ACT scores are scaled from 1 to 36.

More than 21,500 Utah students — 69 percent of the graduating class — took the exam; about 1,000 more than in the class of 2005.

Just under half of test-takers were enrolled in rigorous "core" coursework, which ACT defines as four years of language arts and three years each of math, science and social studies.

State Superintendent of Public Instruction Patti Harrington called all that "good news."

"In addition, the percentage of minority students taking the test is slightly increasing for some subgroups. This, too, is hopeful," she said in a prepared statement.

But ethnic minority scores trail whites'. Caucasians' composite averaged a 22 — mirroring the national score for that group. Blacks and American Indian/Alaska natives averaged an 18.2, Hispanics a 19.3, and Asian American/Pacific Islanders averaged 20.7.

All Utah group scores, except those for "other" ethnicity/no response and Asian American/Pacific Islanders, improved from last year. And all but American Indian/Alaska native and Asian American/Pacific Islanders met or beat national averages.

A rigorous class schedule is known to boost ACT scores; overall, students who took the ACT-recommended "core" regimen averaged a 22.6 composite score versus 20.7 for those who didn't.

Half of Caucasians reported taking the ACT core regimen, and their composite averaged 22.9.

But 51 percent of Hispanics took the core regimen and averaged a 20 composite, well below Caucasians. Sixty percent of Asian American/Pacific Islanders reported taking "core or more" and averaged a 21.4.

Granted, those ethnic groups are far smaller than Caucasians, who numbered nearly 17,000 test-takers versus 801 Hispanics and 694 Asian American/Pacific Islanders, for example. The smaller the group, the more volatile the scores.