Two years after many colleges resisted attempts by the Bush administration to impose more rigorous methods of student assessment, a leading coalition of private institutions is pressing its members to adopt an increasingly popular standardized achievement test. The push to adopt the assessment comes as the test faces new questions over its reliability. Last week the 600-member Council of Independent Colleges accepted a $666,000 grant from the Teagle Foundation to expand a consortium through which the council's members promote the use of the Collegiate Learning Assessment, which is designed to test skills like critical thinking, problem solving, and writing. The test, known as the CLA, is given to college students in their freshman and senior years. Two studies presented last week at the annual conference of the Association for Institutional Research, in Seattle, challenge the CLA's method of calculating the added value an institution gives its students. A fix to the way the test is administered that would make that calculation more meaningful would be simple but costly, the researchers say.