Intro
Student Growth Percentiles and Accountability
References
An Introduction to Student Growth Percentiles
Damian W. Betebenner
National Center for the Improvement of Educational Assessment
Dover, NH
University of Massachusetts, Amherst
Amherst, Massachusetts
March 9th, 2012
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
About Me
Damian Betebenner
- Senior Associate at the Center for Assessment (NCIEA).
- Developed student growth percentiles and percentile growth
trajectories to help states and educational associations employ
student growth in decision making [Betebenner, 2008,
Betebenner, 2009, Betebenner, 2012].
- Currently refining and sharing these techniques with other
states including Colorado, Massachusetts, Indiana, Nevada and
approximately 25 other states in various stages of
investigation/adoption.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Describing Student Growth
Measuring student growth, even with a vertical scale, is not a simple
task.
Some believe a vertical scale simplifies the task of measuring
student growth.
Even with an interval (or ratio) scale, growth is not easy to interpret.
Consider, for example, height.
A child might grow 4 inches between ages 3 and 4.
4 inches is a well understood quantity.
The 4 inch increase becomes really meaningful only when understood
alongside the growth of other 3 to 4 year olds.
Student growth percentiles were developed to provide a
norm-referenced description of student growth (i.e., a growth norm).
Damian W. Betebenner An Introduction to Student Growth Percentiles
20 core
ca ca le
le 280
S re 2012
co
20 core
ca ca le
le 280
S re 2012
co
20 core
ca ca le
le 280
S re 2012
co
co
th 260
re
ro
i le
le
nt ca
er
ce
th
260 re
co
240 le
ca
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Student Growth Percentiles
Should we be surprised with a child’s current achievement given their prior
achievement?
Given a student’s prior scale scores and the associated conditional
density, their current scale score corresponds to a percentile of that
conditional distribution.
This percentile is the student’s growth percentile.
Growth percentiles are closely related to estimating the probability of
observing a student’s current achievement taking account of their
past achievement:
Pr(Current Achievement |Past Achievement ).
As such, growth percentiles describe the rarity of a student’s current
achievement conditional upon their prior achievement.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Student Growth Percentiles
Should we be surprised with a child’s current achievement given their
prior achievement?
Student growth percentiles answer this question.
Consider a low achieving student with 50th percentile growth and a
high achieving student with 50th percentile growth.
The low achieving student grew at a rate exceeding 50 percent of
similar students.
The high achieving student grew at a rate exceeding just 50 percent of
similar students.
The low achiever’s growth is probabilistically equivalent to the high
achiever’s.
Equally rare does not imply equally good!
Judgments about the adequacy of student growth require external
criteria. That is, criterion referencing.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Model for Student Growth Percentiles
Student growth percentiles are calculated using quantile regression
with B-spline smoothing, a generalized additive model.
Quantile regression is used to model the complete distribution of the
response variable (current achievement)
B-spline smoothing is uses to accommodate non-linearity and
heteroscedasticity of the data.
The model/method is descriptive and all about data fit—it’s a data
mining procedure.
The model quantifies distance = rate · time probabilistically.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Model for Student Growth Percentiles
Conditional Decile Regression Curves Conditional Decile Regression Lines
2006−07 Math: Grade 5 versus 6 2006−07 Math: Grade 5 versus 6
1000 Unsatisfactory Partially Prof. 1000 Unsatisfactory Partially Prof.
Proficient Proficient
Partially Prof. Proficient Advanced Partially Prof. Proficient Advanced
Grade 6 Scale Score Grade 6 Scale Score
Grade 5 Scale Score Grade 5 Scale Score
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Software for Student Growth Percentiles
Student Growth Percentiles and Percentile Growth Trajectories are
calculated using the open source R Software
Environment [R Development Core Team, 2011] and the SGP
package [Betebenner and VanIwaarden, 2012]
In working with state departments of education, the goal is to build
state capacity so states can perform and validate their own analyses
using software available and easily used by the state.
Colorado, Massachusetts, Indiana, Nevada, Arizona, Wisconsin are
states (that I know of) who have state staff capable of generating the
student growth percentiles together with aggregations that follow
from their calculation.
State ownership/oversight of the SGP calculations has been a big
plus in terms of buy-in from the state, enhancing their ability to
explain and work with local stakeholders.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Describing Student Growth
Intro
Student Growth Percentiles
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
References
Criterion Referenced Growth
Establishing growth-standards based upon growth-norms
The most common adequacy criterion are judging growth toward an
achievement goal (i.e., growth-to-standard).
Results from student growth percentile analyses can be used to
calculate percentile growth trajectories for each student.
These trajectories indicate what future rates of growth will lead to
and are used to make adequacy judgments.
This growth-to-standard approach was approved as part of
Colorado’s successful application to the Growth Model Pilot
Program.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Advanced Reading
High
Achievement
CSAP Reading
● Typical
Scale Score
Proficient Growth
Low
● Level Percentiles
High 66th − 99th
Typical 35th − 65th
Part Proficient
● Low 1st − 34th
Unsatisfactory
Grade 3 Grade 4 Grade 5 Grade 6 Next Year
Scale Score 462 539 563 609
Achievement Level Unsatisfactory Part Proficient Part Proficient Proficient Achievement
Growth Percentile 66 66 90
Growth Level High High High Growth
Example Student 12 (1234567812) Sample Middle School
Advanced
Math
Achievement
High
CSAP Math
● Scale Score
Typical
● Growth
Proficient
● Level Percentiles
Low
High 66th − 99th
● Typical 35th − 65th
Part Proficient
Low 1st − 34th
Unsatisfactory
Grade 3 Grade 4 Grade 5 Grade 6 Next Year
Scale Score 379 388 444 462
Achievement Level Part Proficient Part Proficient Part Proficient Part Proficient Achievement
Growth Percentile 16 69 51
Growth Level Low High Typical Growth
Advanced Reading
High
Achievement
CSAP Reading
● Typical
Scale Score
Proficient Growth
Low
● Level Percentiles
High 66th − 99th
Typical 35th − 65th
Part Proficient
● Low 1st − 34th
Unsatisfactory
Grade 3 Grade 4 Grade 5 Grade 6 Next Year
Scale Score 462 539 563 609
Achievement Level Unsatisfactory Part Proficient Part Proficient Proficient Achievement
Growth Percentile 66 66 90
Growth Level High High High Growth
Advanced
Writing
Achievement
High
CSAP Writing
● Scale Score
Typical
● Growth
Proficient
Level Percentiles
● Low
High 66th − 99th
Part Proficient ● Typical 35th − 65th
Low 1st − 34th
Unsatisfactory
Grade 3 Grade 4 Grade 5 Grade 6 Next Year
Scale Score 425 449 469 504
Achievement Level Part Proficient Part Proficient Part Proficient Part Proficient Achievement
Growth Percentile 55 53 79
Growth Level Typical Typical High Growth
Copyright 2009, Colorado Department of Education/Center for Assessment, Inc.
2008 CSAP Mathematics
Growth and Achievement Chart
2008 Achievement Percentile Percentile Growth Trajectory
Scale Score
Grade 3 Grade 4 Grade 5 Grade 6 Grade 7 Grade 8 Grade 9 Grade 10
West Virginia: 2010−2011 Mathematics
Norm & Criterion Referenced Growth to College Readiness
Percentile Growth Trajectory to College Readiness
College Ready
Scale Score
Not College Ready
2010−2011 Achievement Percentile
Grade 3 Grade 4 Grade 5 Grade 6 Grade 7 Grade 8 Grade 9 Grade 10 Grade 11
Hawaii: 2011 Mathematics
Norm & Criterion Referenced Growth & Achievement
2011 Achievement Percentile
Percentile Growth Trajectory
Grade 3 Grade 4 Grade 5 Grade 6 Grade 7 Grade 8
Massachusetts: 2011 ELA
Norm & Criterion Referenced Growth & Achievement
Baseline Referenced Percentile Growth Trajectory
2011 Achievement Percentile
Grade 3 Grade 4 Grade 5 Grade 6 Grade 7 Grade 8
Intro
School Accountability
Student Growth Percentiles and Accountability
Concluding Remarks
References
Going from Students to Schools/Classrooms
It’s of interest to examine schools or classrooms/teachers where
students demonstrate, on average, extraordinarily high and low
student growth.
To summarize the student growth percentiles associated with a
school (or other grouping) calculate the median of the student
growth percentiles.
If students were randomly assigned to schools, expect to see a
median of 50.
Values greatly above or below 50 are of interest in identifying best
practices or providing extra support.
Examining growth with achievement sheds new light on school
performance.
Damian W. Betebenner An Introduction to Student Growth Percentiles
District C: 2008 CSAP Math School Results
Student Growth versus Student Achievement by Percent Free/Reduced Lunch
School Percent
Higher Achievement Higher Achievement Free/Reduced Lunch
Lower Growth Higher Growth
Percent at/above Proficient in School
Less than 20 percent
● 20 to 40 percent
● 40 to 60 percent
● 60 to 80 percent
● More than 80 percent
School Size
50 Students
100 Students
200 Students
30 500 Students
1,000 Students
10 Lower Growth Higher Growth
Lower Achievement Lower Achievement
Median of Student Growth Percentiles in School
Intro
School Accountability
Student Growth Percentiles and Accountability
Concluding Remarks
References
What’s Next?
Many states have publicly released growth results.
The response has been overwhelmingly positive.
Calculating of the quantities is the easy part. Getting people to
understand them and use them correctly is the hard part.
Colorado, Massachusetts, Indiana, Virginia, and other states are
investigating a multi-state platform for data visualization and
reporting built from a common growth analysis.
Damian W. Betebenner An Introduction to Student Growth Percentiles
Student Growth Percentile Adoption
Adopted Model
Considering Adoption
Investigating Model
Intro
Student Growth Percentiles and Accountability
References
References
Betebenner, D. W. (2008).
Toward a normative understanding of student growth.
In Ryan, K. E. and Shepard, L. A., editors, The Future of Test-Based
Educational Accountability, pages 155–170. Taylor & Francis, New
York.
Betebenner, D. W. (2009).
Norm- and criterion-referenced student growth.
Educational Measurement: Issues and Practice, 28(4):42–51.
Betebenner, D. W. (2012).
Growth, standards, and accountability.
In Cizek, G., editor, Setting Performance Standards: Foundations,
Methods, and Innovations, pages 439–450. Routledge, New York.
Betebenner, D. W. and VanIwaarden, A. (2012).
SGP: An R Package for the Calculation and Visualization of Student
Growth Percentiles.
R package version 0.8-0.0.
R Development Core Team (2011).
R: A language and environment for statistical computing.
R Foundation for Statistical Computing, Vienna, Austria.
Damian W. Betebenner An Introduction to Student Growth Percentiles
About this copy
An Introduction to Student Growth Percentiles — UMASS Amherst, March 9, 2012.
This is an image-based copy of the original beamer slides; builds and animations are flattened.