Study Says 'Plateau Effect' Not Pervasive
"Is There a Plateau Effect in Test Scores?"
One of the common beliefs about testing in the era of accountability holds that student test scores improve rapidly in the first few years of a new testing program, but are followed by a plateau in scores as it becomes harder for educators to bump up the performance of students with learning challenges.
But a recent report offers evidence that, while this “plateau effect” in test scores does appear in some states, it is not pervasive across the nation. In fact, test-score trends are as likely to increase or to decrease as they are to plateau.
The study, released last month by the Washington-based Center on Education Policy, examines 55 state test-score trends across 16 states. Each of the trend lines represents at least six years of test-score data between 1999 and 2008. Noneof the states studied changed those tests over that period or lowered their “cut scores,” the number or percentage of questions students must answer correctly to be deemed “proficient.”
Of the 55 trend lines studied, 15 exhibited a plateau. Twenty-one trend lines showed steady increases in the percentage of students scoring at the proficient level on the tests, while 19 states showed a zigzag pattern that, despite some downturns, indicated overall upward momentum.
The findings contrast with earlier studies that found evidence of the plateau phenomenon. The authors suggest that those earlier studies were largely conducted with data from the 1980s and 1990s. In those years, before state and federal accountability regimes began putting a premium on using fresh test items each year, it was easier to prepare students for tests.
Vol. 28, Issue 37, Page 4
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