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EVAAS Concepts: NCEs and Standard Errors Sandy Horn January 2013

EVAAS Concepts: NCEs and Standard Errors Sandy Horn January 2013. SAS ® EVAAS ® for K-12. Similarities between the EVAAS Growth Standard Model and the Predictive Model. For both models:

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EVAAS Concepts: NCEs and Standard Errors Sandy Horn January 2013

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  1. EVAAS Concepts:NCEs and Standard ErrorsSandy HornJanuary 2013 SAS® EVAAS® for K-12

  2. Similarities between the EVAAS Growth Standard Model and the Predictive Model For both models: Progress is measured relative to the average progress for a grade/subject in North Carolina in the year tested. Average Progress/Growth Standard is 0.0. Standard errors determine whether a district, school, or teacher’s growth measure is different from average. (More on this, shortly)

  3. Differences between the EVAAS Growth Standard Model and the Predictive Model Growth Standard Model Predictive Model Can be used with tests, whether administered sequentially or not. Requires at least three prior test scores to predict where students will score, relative to other NC students who take the same test. (Prior scores don’t have to be in the subject being analyzed.) • Only used with tests administered in sequential years. • Does not predict where students will score, so doesn’t need three prior test scores.

  4. Differences between the EVAAS Growth Standard Model and the Predictive Model Growth Standard Model Predictive Model Measures the difference between where students would be expected to score, assuming the average progress, statewide, and where they did score, when tested. Reported in Scale Score Points. • Measures the difference between a cohort’s position in the state distribution in a grade/subject at the end of one year and their position in that distribution at the end of the next year. • Reported in NCEs.

  5. Growth Standard Value Added Report

  6. Normal Curve Equivalent Units - NCEs

  7. NCEs and the Growth Standard 5th Grade: NCE 37 6th Grade: NCE 37 30 40 50 60 70 30 40 50 60 70 6th grade NCE 37 ― 5th grade NCE 37 = 0 = State Growth Standard The State Growth Standard (0.0) is achieved when students do not lose ground from year to year, relative to other students, across the state, who take the same test. It signifies one year’s growth.

  8. Growth Standard Value Added Report

  9. What are Standard Errors, and Why aren’t they all the same? Standard Errors let us know how confident we can be that a sample approximates a population. In other words, how sure can we be that our students (a sample) made progress similar to or different from the progress that is average for all the students in North Carolina (the population)? If we have a lot of students and/or a lot of data points (test scores) and/or somewhat complete data for our sample and so on, we can be pretty precise in estimating the progress of that group of students. The standard error would be small. If we have few students and/or few data points and/or very spotty data, we can’t be as certain of the estimated progress of that group of students. The Standard Error would be large.

  10. Standard Errors are Protection against Misclassification Small negatives and small positives may not be significantly different from Average. The standard error lets you know whether the difference is significant or not. Unless there is strong evidence to the contrary, standard errors ensure that an estimate is considered “Average.” They protect districts, schools, and teachers from being misclassified as different from Average unless there is a significant difference.

  11. About those Standard Errors…How much confidence do we have that the estimate is different from 0.0? 80% 80% 90% 90% 95%+ 95%+ 99% 99% -3se -2se -1se +1se +2se +3se 0.0 Growth Standard State Average Exceeds Expected Growth Does Not Meet Expected Growth Meets Expected Growth

  12. About those Standard Errors…How much confidence do we have that the estimate is different from 0.0? 5th Grade: NCE 37 6th Grade: NCE 38.8 +1.8 NCEs above 0.0 0.0 Growth Measure: 1.8 NCEs/points 30 40 50 60 70 30 40 50 60 70 6th grade NCE 38.8 ― 5th grade NCE 37 = 1.8 NCEs Is it different from the State Growth Standard?

  13. About those Standard Errors…How much confidence do we have that the estimate is different from 0.0? School 1: Growth Measure: 1.8 NCEs SE: 1.1 NCEs +/- 2 SEs = 2.2 NCEs School 2: Growth Measure: 1.8 NCEs SE: 0.8 NCEs +/- 2 SEs = 1.6 NCEs +2.2 NCEs +1.6 NCEs +1.8 NCEs above 0.0 -1.6 NCEs Growth Std/State Avg (0.0) -2.2 NCEs School 1 Meets Expected Growth because its Growth Measure is less than 2 SEs above or below the Growth Standard. School 2 Exceeds Expected Growth because its Growth Measure is 2 SEs or more above the Growth Standard. It works just the same for the Predictive Model. Just change NCE to Scale Score and Growth Standard to State Average.

  14. Growth Standard Value Added Report

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