Overview
Growth Model Background
Student Growth Percentiles and Accountability
References
New Directions for Student Growth Models
Damian W. Betebenner
National Center for the Improvement of Educational Assessment
Dover, NH
The Neag Graduate Student Association (NGSA) Colloquium
October 14th, 2010
Damian W. Betebenner New Directions for Student Growth Models
Overview
Growth Model Background
About Me
Student Growth Percentiles and Accountability
References
About Me Past & Present
???? – 2001 Professional Student. Received a Ph.D. in Mathematics in
1995 from University of Wyoming and a Ph.D. in Education
(Research & Evaluation Methodology) University of
Colorado, Boulder, 2001.
2001 – 2004 Post-Doc. University of Colorado, Boulder
2004 – 2007 Assistant Professor, Boston College, Department of
Education Research Measurement and Evaluation
2007 – ???? Senior Associate, National Center for the Improvement of
Educational Assessment
Damian W. Betebenner New Directions for Student Growth Models
Overview
Growth Model Background
About Me
Student Growth Percentiles and Accountability
References
About Me Past & Present
Current Responsibilities Work with state departments of education and
affiliated organizations on the development of student
growth models. Developed student growth percentiles and
percentile growth trajectories[Betebenner, 2008] to help
states discuss student growth. Currently refining and
sharing these techniques with other states including
Massachusetts, Colorado, Nevada, Indiana, South
Carolina, Arizona, Rhode Island
Current Interests The rise of the data scientist: Data analysis and data
visualization and their intersection with education
Damian W. Betebenner New Directions for Student Growth Models
Overview
Growth Model Background
About Me
Student Growth Percentiles and Accountability
References
About Data Science
Damian W. Betebenner New Directions for Student Growth Models
Overview
Growth Model Background
About Me
Student Growth Percentiles and Accountability
References
About Today’s Discussion
Growth Models: What’s the big deal?
Student growth percentiles and percentile growth
projections/trajectories
A growth model isn’t an end, it’s just a means embedded within a
larger theory of action (e.g., high-stakes accountability)
Damian W. Betebenner New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
Criterion Referenced Growth
Growth Model Background
Advanced data collection and administration combined with annual
testing has allowed longitudinal student level data
Investigating data longitudinally allows for numerous questions to be
investigated that were not possible with cross sectional data
It is critical, however, to let questions precede data analysis and not
vice-versa
Damian W. Betebenner New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
Criterion Referenced Growth
Descriptive Questions
Note that the questions put forward by stakeholders are primarily
descriptive
The questions are only peripherally associated with causality.
High stakes accountability has transformed questions about student
growth into questions about responsibility/cause: Teacher and
School Effectiveness.
Again, starting with descriptive questions, perhaps the place to
begin is with description and a model supporting such ends.
Damian W. Betebenner New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
Criterion Referenced Growth
Descriptive Accountability
Accountability system results can have value without making
causal inferences about school quality, solely from the results of
student achievement measures and demographic
characteristics. Treating the results as descriptive information
and for identification of schools that require more intensive
investigation of organizational and instructional process
characteristics are potentially of considerable value. Rather
than using the results of the accountability system as the sole
determiner of sanctions for schools, they could be used to flag
schools that need more intensive investigation to reach sound
conclusions about needed improvements or judgments about
quality [Linn, 2008, p. 21].
Damian W. Betebenner New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
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Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
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 New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
Criterion Referenced Growth
Description, Inference, and Causality
Richard Berk in Regression Analysis, A Constructive Critique (2003)
provides an account of the (ab)use of regression
Three Cheers for Description Descriptive models are judged by their
utility
Two Cheers for Inference Inferential models are judged based upon their
ability to fulfill statistical criteria associated with
generalizing from a sample to a population. What is the
chance process?
One Cheer for Causality Causal models are judged, in addition to
inferential issues, by an external theory which plausibly
relates causes/interventions and effects/outcomes.
Damian W. Betebenner New Directions for Student Growth Models
Relevant Questions/Concepts
Overview Description, Inference, and Causality
Growth Model Background Describing Student Growth
Student Growth Percentiles and Accountability Student Growth Percentiles
References Model & Software for Student Growth Percentiles
Criterion Referenced Growth
Combining Normative and Criterion-Referenced Growth
Growth adequacy is determined by whether a student’s growth is
sufficient to reach/maintain desired achievement levels (e.g.,
proficiency).
Percentile growth projections/trajectories are calculated for each
student using the most recent historical MCAS longitudinal student
growth analyses.
These “growth-to-standard” trajectories indicate what it will take for
the student to reach/maintain proficiency and other achievement
levels.
This approach to quantifying “adequate” growth (done by Colorado)
was approved by the USED for use in AYP determinations as part of
the Growth Model Pilot Program.
Damian W. Betebenner New Directions for Student Growth Models
Overview
School Accountability
Growth Model Background
Growth & Effectiveness
Student Growth Percentiles and Accountability
Concluding Remarks
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 New Directions for Student Growth Models
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
Overview
School Accountability
Growth Model Background
Growth & Effectiveness
Student Growth Percentiles and Accountability
Concluding Remarks
References
Growth, Effectiveness, and Value-Added
Fundamental Premise
“Good” schools bring about student growth in excess of that found at
“bad” schools.
“Good schools” are often called highly effective schools.
What’s the relationship between growth and effectiveness?
Effectiveness indicates who/what is responsible for the growth
(value-added models).
Damian W. Betebenner New Directions for Student Growth Models
2009 CSAP Elementary School Mathematics:
School Poverty by School Achievement (r = −0.71)
80 Higher Achievement
Percent at/above Proficient
Lower Achievement
Percent Free/Reduced Lunch Students at School
2009 CSAP Elementary School Mathematics:
School Poverty by School Median SGP (r = −0.22)
80 Higher Average Growth
Median Student Growth Percentile
20 Lower Average Growth
Percent Free/Reduced Lunch Students at School
2009 CSAP Elementary School Reading:
School Poverty by School Median SGP (r = −0.25)
80 Higher Average Growth
Median Student Growth Percentile
20 Lower Average Growth
Percent Free/Reduced Lunch Students at School
Economic Disadvantage vs School Effectiveness
TN Elementary Schools 2008
Average Yearly Achievement Gain 1
Math & Reading/Language Arts in Z units from
TN Current State Average
Percent Free & Reduced Lunch
Composite VA Gain by %
Poverty
School % Poverty
Figure 4c: Grade 6 (2006) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size >= 50)
Prior Achievement
1st Quintile
2nd Quintile
● ● 3rd Quintile
4th Quintile
Median Student Growth Percentile
70 ●●●● 5th Quintile
●●●● School Size
25 Students
● 50 Students
100 Students
●● ● 250 Students
● ● 500 Students
Value−Added Estimate from Layered Model
Figure 5a: Grade 4 (2004) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size > 50)
Prior Achievement
1st Quintile
Median Student Growth Percentile
●● ● School Size
● ●● 25 Students
●● 50 Students
●● ● ● ● ● 100 Students
250 Students
500 Students
Value−Added Estimate from Layered Model
Figure 6a: Grade 4 (2004) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size > 50)
Prior Achievement
2nd Quintile
Median Student Growth Percentile
60 ●●● School Size
● 25 Students
●● 50 Students
●● ● 100 Students
● 250 Students
● ● ● 500 Students
Value−Added Estimate from Layered Model
Figure 7a: Grade 4 (2004) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size > 50)
Prior Achievement
3rd Quintile
Median Student Growth Percentile
60 ●●●● School Size
●● 25 Students
● ● ● ● 50 Students
● 100 Students
● ● ●● 250 Students
30 ● ●●● ● 500 Students
Value−Added Estimate from Layered Model
Figure 8a: Grade 4 (2004) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size > 50)
Prior Achievement
●● 4th Quintile
Median Student Growth Percentile
60 ● ● ● ●● ● ● School Size
25 Students
50 ● 50 Students
100 Students
●●● 250 Students
30 ● 500 Students
Value−Added Estimate from Layered Model
Figure 9a: Grade 4 (2004) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size > 50)
Prior Achievement
Median Student Growth Percentile
5th Quintile
● ● ● School Size
●● ● 25 Students
50 ● ●●●●●●● ● ● 50 Students
100 Students
● ● 250 Students
30 ● ● ● 500 Students
Value−Added Estimate from Layered Model
Figure 10a: Grade 4 (2004) Layered Model versus Quantile Regression Estimates (SEP3ML Scale)
by Prior Achievement Quintile (School Size > 50)
Prior Achievement
Median Student Growth Percentile
● 10th Decile
60 ● ● ● School Size
●● 25 Students
50 ● ● ●● 50 Students
100 Students
250 Students
30 ● 500 Students
Value−Added Estimate from Layered Model
Overview
School Accountability
Growth Model Background
Growth & Effectiveness
Student Growth Percentiles and Accountability
Concluding Remarks
References
What’s Next?
Colorado and Massachusetts 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, Arizona, and other states are
investigating a multi-state platform for data visualization and
reporting built from a common growth analysis.
Damian W. Betebenner New Directions for Student Growth Models
Overview
Growth Model Background
Student Growth Percentiles and Accountability
References
References
Berk, R. A. (2003).
Regression Analysis: A Constructive Critique.
Sage, Thousand Oaks, CA.
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.
Linn, R. L. (2008).
Educational accountability systems.
In The Future of Test-Based Educational Accountability, pages 3–24.
Taylor & Francis, New York.
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 New Directions for Student Growth Models
About this copy
New Directions for Student Growth Models — UCONN Colloquium, November 16, 2009.
This is an image-based copy of the original beamer slides; builds and animations are flattened.