1. Normal Curve Equivalent
Scores on standardized tests like TCAP are distributed in a typical bell curve.
In a normal curve, 68% of students scores within 1 standard deviation on either side of the mean, and 95% of students scores within two standard deviations, and kids who score really high or really low – the tails of this curve – represent only about 5% of the students in total.
Graphic from

2. Normal Curve Equivalent
From the perspective of percentiles, the 75th percentile - the point that 75% of students score below - is actually in the middle part of this curve, within 1 standard deviation of the mean.
If you displayed all the percentiles on a straight line, you would see that they cluster in the middle, under the “bell”.
So if you talked about someone moving 4 “percentiles” from the year before, that means something a lot different going from 95th to 99th than to go from the 50th to the 54th percentile.
But there is value in being able to look at a “number line” like this and talk meaningfully about moving kids’ up or down from year to year and do numerical calculations on that movement. That how the “normal curve equivalent”, or NCE, was conceived.
Graphic from

3. Normal Curve Equivalent
The normal curve equivalent is basically a straight line representation of these distribution concepts, where there is even spacing between the segments. So moving an NCE score by 4 means the same no matter if you started at 1 or 81.
Another value of NCE, is that for the purposes of TVAAS, the NCE line was built from is a fixed baseline for comparison; it was created from the bell curve of the test takers in 2009, the first year the standards changed. So an NCE score of 50 means your score was exactly the mean of the 2009 test scores.
It is important to remember that although NCE is built from a layer of statistical calculations, it is ultimately a function of individual students and the number of questions that they answered correctly on a test, and that is ultimately how an NCE score is moved from year to year.
Transition:
Which begs the question of what is a good NCE score?
URL reference to put on final slide:
Graphic from

4. Grade Scale from state report card site
What is a good NCE score?
So, what is a good NCE score, and what does it take to move it?
The state has determined this grading scale for NCE scores, available on the state TNDOE website.
To move from grade to grade, on average it only takes each kid answering one more question correctly.
Grade Scale from state report card site