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Glossary of Terms

Glossary of Terms and Abbreviations Used in Tennessee’s Value-Added Assessment Reports


3-Year-Average NCE Gain

The average academic gain of the most recent 3 years expressed as an NCE (normal curve equivalent) score. These scores represent the average number of NCE points by which a school exceeds or falls short of the student achievement growth that occurred statewide in 1998-the benchmark year, a.k.a., the Growth Standard. These are the scores on which the Value-Added Achievement Awards are based.

Average Normalized Equivalent Score

Average of a school’s normalized Mean NCE Gain over 2 or more Grades in math and reading.

Composite Math/Reading Score

The average of the normalized math and reading scores for all grades taught by a given school. The normalized math and reading scores are based on each school’s 3-Yr-Avg NCE Gain.

Composite Performance Grades

Letter grades based on Tennessee Department of Education grade scales and representing overall school performance in math and reading. These grades are technically accurate, but not identical to the average of the letter grades received by schools in math and reading/language arts.

CRT, or Criterion Referenced Test

A test that provides scores referenced to an established criterion (a fixed point), as opposed to an NRT or Norm Referenced Test that references scores to the average of a group. Tennessee now uses CRTs referenced to statewide averages that were reported in 1998; the purpose of using CRTs in this way is to give schools a constant benchmark against which annual performance can be judged.

Estimated School Mean NCE Gain

The average gain in student achievement made by a given school expressed as an NCE (normal curve equivalent) score relative to the 1998 benchmark scores. For example, if a school has a 2003 Mean NCE Gain in Grade 4 of 5.2, it means that on the average, 4th grade students in this school gained 5.2 NCE points more than 4th graders statewide gained in the baseline year of 1998, i.e., the “Growth Standard” year. As a different example, a school with 2003 Mean NCE Gain in Grade 4 of -3.0 would indicate that students were learning 3.0 points less per year than students were gaining in 1998. On the charts provided by the state, school reports are color coded to reflect degrees of growth or decline.

Estimated School Mean NCE Scores

A school’s average scores on the TCAP test arranged by grade and year, and expressed as NCE (normal curve equivalent) scores. Scores greater than 50 indicate that a school’s TCAP scores are above the 1998 statewide average; scores less than 50 are below the 1998 average. For example, a school with a 2005 Mean of 64.7 for grade 4 may be said to have TCAP scores that are approximately at the 65th percentile of Tennessee’s 1998 TCAP achievement test distribution.

Growth Standard

The 1998 Tennessee statewide average achievement gain in each subject and grade. The Growth Standard is the benchmark against which achievement gains in Tennessee are now judged. It is represented by the midline on the School Effectiveness chart.

Mean NCE Gain over Grades

The average of the 3-Yr-Average NCE Gain scores reported for each school, in each subject. They represent the average improvement or decline in school effectiveness relative to the state average of effectiveness in 1998, i.e., the Growth Standard.

NCE, or Normal Curve Equivalent

A test score reported on a scale that ranges from 1 to 99 with an average of 50. NCE’s are are approximately equal to percentiles. For example, an NCE of 70 is approximately equal to or greater than 70% of its reference group. Assuming a normally distributed population, plotting the distribution of scores will result in a bell shape commonly known as a bell curve.

Normalized Scores

Scores that have been converted to a standard scale with a mean of zero and a standard deviation of 1. Plotting the distribution of scores, assuming a normal distribution, will result in a bell shape commonly known as a bell curve.

Standard Error

All averages are imperfect estimates; the standard error demonstrates the possible range of actual scores within a 68% likelihood. For example, if a school’s 2003 Mean NCE Gain in Grade 4 was 5.2 and the Std Error was 1.0, there would be a 68% chance that the true NCE score for the school is somewhere between 4.2 and 6.2. Fallible estimates and standard errors notwithstanding, the “best estimate” of the true score (i.e., the true performance level for a given school) is the average, and thus averages are used to report school performance.

Estimated School Mean NCE Gain (State 3 Year Average)

The average achievement gain of all Tennessee schools in a given subject and grade level for the most recent 3 years. Due to a variety of factors including curriculum changes, the statewide 3-year averages are up in some grades and subjects and down in others. By comparing a school’s present NCE gains with the 3-year average, it is possible to see how far that school has come since 1998 relative to the progress made by other schools statewide.

Estimated School Mean NCE Scores (State 3 Year Average)

The statewide average of TCAP test scores for the most recent 3 years. The scores of individual schools can be compared to this number to gauge relative performance. As an example: if a school’s 5th grade 2005 Mean NCE score is 70 and the state 3-Year Average is 52, the school’s score is outperforming the average (and technically, is approximately equal to or greater than those of 68% of other 5th grades statewide).

State Base Year (1998)

The statewide average of TCAP test scores in 1998. These scores serve as a benchmark; test score averages in all subsequent years are reported using them as a reference. The 1998 statewide average is defined as an NCE score of 50.

TCAP, or Tennessee Comprehensive Assessment Program

The Tennessee-customized version of McGraw Hill’s nationally published Terra Nova test. This is a series of tests that the state of Tennessee uses to gauge student achievement. The TCAP currently includes the Achievement Test (grades 3-8), the Writing Test, the Competency Test, the Gateway Tests and the End of Course Tests.

TVAAS, or Tennessee Value Added Assessment System

The name of the accountability system created for Tennessee by Dr. William Sanders. It is based on the use of value-added data to determine the true annual academic progress of students and schools.

Value-Added Assessment

An accountability system that measures annual growth in student achievement. Each student is compared to his or her previous performance; and through the use of sophisticated statistical models, pre-existing social, economic, and demographic differences are removed leaving more accurate estimates of actual achievement gain. It permits teachers, schools, and school districts to be compared on a level playing field. Note: Not all value-added assessment systems are the same. TVAAS uses “mixed model analysis.” Simpler versions using less sophisticated statistics may produce misleading results.

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