Overview
SGP
Student Growth Percentiles and Accountability
Future Directions
References
Student Growth Percentiles: An Overview
Damian W. Betebenner & Adam VanIWaarden
National Center for the Improvement of Educational Assessment
Dover, NH
Needham, Massachusetts March 29th, 2023
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability About me
Future Directions
References
About Me
Dr. Damian Betebenner, PhD
- 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 more than
25 states in the United States, testing companies (Renaissance
Learning), and other countries including Australia.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability About me
Future Directions
References
About Me
Dr. Damian Betebenner, PhD
- Educational Background: PhD in Education Measurement from
the University of Colorado, Boulder and a PhD in Mathematics
from the University of Wyoming.
- Began using R in 1999 to produce high quality graphics and it
has been seminal in expanding my work.
- I’m more of a "data scientist" than a statistician. SGPs are more
of a "data science" approach to examining student academic
growth than a "statistician" approach.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability About me
Future Directions
References
Student Growth Percentiles
2007 Began develop of the Colorado Growth Model (student
growth percentiles).
2008 Successful application of Colorado Growth Model
(criterion-referenced component) as part of growth model
pilot program.
2009-2010 Began/continued work with approximately two-dozen other
states on developing state growth models.
2010 Worked with states on incorporating growth into RttT
applications and with successful states on their use
(Massachusetts, Georgia, New York, Rhode Island).
2011 Worked with a number of states on incorporating student
growth percentiles into the ESEA waiver applications and
teacher evaluation systems.
2012 Worked with 5 states on co-developing interactive
visualizations to help better communicate student growth
percentile results. Current 18 states have signed an MOU
to participate in visualization work and share resources
they develop around the growth model.
2014 Built SIMEX measurement error correction into SGP
model [Shang et al., 2015]
2014 Extended analyses to accommodate time-dependency
allowing for SGP modelling of interim assessments.
2017 Extended SGP package to better accommodate
assessment transitions.
2020-2023 Utilized SGPs to examine academic impact and recovery
due to the COVID-19 pandemic.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability About me
Future Directions
References
About the growth model
The Student Growth Percentiles Methodology is a norm- and
criterion-referenced growth analysis method.
The norm-referenced component of the model is the student growth
percentile which indicates the relative growth a student makes.
The criterion-referenced component of the model is the student
growth percentile target which indicates the amount of growth
required by the student to reach/maintain desirable achievement
goals in a specified time frame. For example, catching-up to
proficiency within 3 years.
The norm- and criterion-referenced components together allow
stakeholders to understand what is, what should be, and what is
reasonable simultaneously.
The goal of the metric was to assist states to move beyond debates
over what thermometer is best to discussions of how best to use the
thermometer.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability About me
Future Directions
References
Built to maximize sharing
A number of analytic tools (for doing calculations) and visualization tools
have been developed with the goal to promote maximum sharing. Data
isn’t valuable! It’s what one does with data that is potentially valuable!
The analytic tools to calculate all the quantities associated with
student growth percentiles are open source and freely available to
all states [Betebenner et al., 2023]. sgp.io
Conduct training sessions at national conferences to help others
calculate these quantities on their own.
Build enhanced visualization and reporting systems to make data
come alive to stakeholders, allow for stakeholder collaboration and
sharing, and lead to better stakeholder engagement with data.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability About me
Future Directions
References
Lessons Learned
On Questions John Tukey
It is better to have an approximate answer to the right question than a precise answer
to the wrong question.
On Statistical Models George E. P. Box
All models are wrong but some are useful.
On Understanding Aristotle
We understand best those things we see emerge from their very beginnings.
On Accountability Sherlock Holmes
It is a capital mistake to theorize before you have all the evidence. It biases the judg-
ment.
On Theories of Action Confucius
Tell me and I will forget, show me and I will remember, involve me and I will understand.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions Student Growth Percentiles
References Criterion Referenced Growth
Guiding Questions
Growth models address specific questions
Different growth analysis techniques are good at answering
different questions.
It is critical to understand these different questions.
Different questions lead to different conversations which lead to
different uses and outcomes.
Changing conversations about education
Starting with the right questions simplifies development and
motivating the proper use of the growth model results.
The questions set the table for those conversations.
Yen (2007) for an excellent list of questions derived from a
survey of parent, teachers and administrators
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions Student Growth Percentiles
References Criterion Referenced Growth
What are the relevant questions for parents?
Yen (2007), from a state survey of parents, teachers and administrators,
compiled a list of frequently voiced questions/concerns by stakeholder
group.
Parent Questions
Did my child make a year’s worth of progress in a year?
Is my child growing appropriately toward meeting state
standards?
Is my child growing as much in Math as Reading?
Did my child grow as much this year as last year?
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions Student Growth Percentiles
References Criterion Referenced Growth
What are the relevant questions for teachers?
Yen (2007), from a state survey of parents, teachers and administrators,
compiled a list of frequently voiced questions/concerns by stakeholder
group.
Teacher Questions
Did my students make a year’s worth of progress in a year?
Did my students grow appropriately toward meeting state
standards?
How close are my students to becoming Proficient?
Are there students with unusually low growth who need special
attention?
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions Student Growth Percentiles
References Criterion Referenced Growth
What are the relevant questions for administrators?
Yen (2007), from a state survey of parents, teachers and administrators,
compiled a list of frequently voiced questions/concerns by stakeholder
group.
Administrator Questions
Did the students in our district/school make a year’s worth of
progress in all content areas?
Are our students growing appropriately toward meeting state
standards?
Does this school/program show as much growth as that one?
Can I measure student growth even for students who do not
change proficiency categories?
Can I pool together results from different grades to draw
summary conclusions?
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions Student Growth Percentiles
References Criterion Referenced Growth
What are the relevant questions for policy makers?
Policy Maker Questions
Can/how should student growth be used in judgments of
educator quality?
Can/how should student growth be used in judgments of
education (e.g., school) quality?
Are students on track for career and college readiness?
What adjustments for student demographics need to be
considered?
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions 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 normative
context for describing student growth.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
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Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions 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 & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions 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 90th percentile growth and a
high achieving student with 10th percentile growth.
The low achieving student grew at a rate exceeding 90 percent of
similar students.
The high achieving student grew at a rate exceeding just 10 percent of
similar students.
The low achiever’s growth is more exemplary (probabilistically) than
the high achiever’s.
Judgments about the adequacy of student growth require external
criteria.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview Different Models/Different Questions
SGP It’s all about conversations starting with questions
Student Growth Percentiles and Accountability Describing Student Growth
Future Directions 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 & Adam VanIwaarden Student Growth Percentiles: An Overview
Devyn Mendoza Sample School
How to interpret this student
growth & achievement report Mathematics
Advanced Achievement
DEMO Catch Up
Target
DEMO Mathematics
Catch Up Scale Score
Scale Score Target
Growth
Proficient Level Percentiles
DEMO Very High 81st − 99th
Achievement Part Proficient
High 61st − 80th
Levels Typical 40th − 60th
Low 20th − 39th
Unsatisfactory Very Low 1st − 19th
Student
Grade 5 Grade 6 Grade 7 Grade 8 Grade 9
Growth 2018−2019 2019−2020 2020−2021 2021−2022 2022−2023
Percentile Scale Score 493 538 519 570
Achievement Level
Achievement Target
Part Proficient Proficient Part Proficient
Proficient (577)
Part Proficient
Proficient (599)
Achievement
Growth Percentile 82 15 71
Catch Up/Keep Up Growth Level Very High Very Low High
Growth
Growth Target Catch Up (83) Catch Up (96)
Move Up/Stay Up
Targets
Suggested Uses
Advanced Reading
Move Up Achievement
Target
DEMO Reading
Scale Score
Review past growth to assess
student academic progress toward Keep Up Growth
Proficient Catch Up
DEMO achievement goals. Target Target
Level Percentiles
Develop remediation or enrich− Very High 81st − 99th
ment plans based on rate of
High 61st − 80th
growth needed to reach higher Part Proficient Typical 40th − 60th
DEMO achievement levels.
Low 20th − 39th
Identify the rate of progress
needed in order to reach or Unsatisfactory Very Low 1st − 19th
maintain proficient status
Grade 5 Grade 6 Grade 7 Grade 8 Grade 9
on the DEMO next year. 2018−2019 2019−2020 2020−2021 2021−2022 2022−2023
Scale Score 653 631 617 649
Achievement Level
Achievement Target
Proficient Proficient Part Proficient
Proficient (632)
Proficient
Proficient (642)/Advanced (691)
Achievement
Growth Percentile 27 10 56
Growth Level
Growth Target
Low Very Low Typical
Catch Up (29) Keep Up (25)/Move Up (99)
Growth
For more information please visit the Student Growth Percentiles Package (the SGP Package) at www.sgp.io or contact dbetebenner@nciea.org
Cooperatively developed by the SGP Package & the Center for Assessment, Inc. Distributed by the SGP Package.
Demonstration: 2021−2022 Mathematics
Norm & Criterion Referenced Growth & Achievement
College Ready
Percentile Growth Trajectory to College Readiness
Scale Score
2021−2022 Achievement Percentile
Not College Ready
SGP trajectories for a 3rd grade student starting from the Level 1/Level 2 cut.
Grade 3 Grade 4 Grade 5 Grade 6 Grade 7 Grade 8 Grade 9 Grade 10
Overview
SGP
School Accountability
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
Future Directions
References
Going from Students to Schools
It’s of interest to examine schools 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 & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
School Accountability
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
Future Directions
References
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 & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
School Accountability
Student Growth Percentiles and Accountability
Model & Software for Student Growth Percentiles
Future Directions
References
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 & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability Descriptive Accountability
Future Directions
References
Descriptive Accountability
“This is the difference between a retrospective question of identifying
fault as opposed to a prospective strategy to engineer some corrective
measure, almost independent of considering whether there was
blame-worthiness. And to move away from the blame-worthiness
paradigm toward something that is more regulatory in nature where one
might seize upon disparities or circumstances that are for some reason
deemed unacceptable and engineer the interventions needed to bring
about the necessary change. . . . It’s the no-fault gap closing strategy in
which the effort is to build a consensus about a vision of an improved
society rather than figure out where’s the person we want to pillory.”
C. Edley (2006)
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
Overview
SGP
Student Growth Percentiles and Accountability
Future Directions
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., Iwaarden, A. V., Domingue, B., and Shang, Y.
SGP: Student growth percentiles & percentile growth trajectories.
Available online complete with source code from https://sgp.io.
Edley, C. (2006).
Educational “Opportunity" is the highest civil rights priority. So what
should researchers and lawyers do about it?
Retrieved June 22, 2006 from the World Wide Web:
http://www.softconference.com/MEDIA/WMP/260407/#43.010.
Shang, Y., VanIwaarden, A., and Betebenner, D. W. (2015).
Covariate measurement error correction for student growth
percentiles using the simex method.
Educational Measurement: Issues and Practice, 34(1):4–14.
Yen, W. M. (2007).
Vertical scaling and No Child Left Behind.
In Dorans, N. J., Pommerich, M., and Holland, P. W., editors, Linking
and Aligning Scores and Scales, pages 273–283. Springer, New
York.
Damian W. Betebenner & Adam VanIwaarden Student Growth Percentiles: An Overview
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Student Growth Percentiles: An Overview — China SGP Presentation, March 29, 2023.
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