Working Papers Series
Papers below are in pdf.
Cory Koedel
WP 09-13
A Non-Experimental Evaluation of
Curricular Effectiveness in Math
Cory Koedel & Rachana Bhatt
This paper uses non-experimental data to evaluate curricular effectiveness. We show that non-experimental methods can be used to obtain causal estimates of curricular effects at just a fraction of what it would cost to produce analogous experimental estimates. Furthermore, external validity concerns that are particularly cogent in the context of curricular evaluations suggest that a non-experimental approach may be preferred. Our results provide important insights for educational administrators and policymakers. In the short term, we find large differences in effectiveness across some math curricula. However, like many educational inputs, the effects of math curricula do not persist over time, a result that would be quite costly to attain using experimental data. Across curricula adoption cycles, publishers that produce less effective curricula in one cycle do not lose market share in the next cycle. One explanation for this result is the dearth of information available to administrators about curricular effectiveness.
JEL Codes: I21, I28 and H75
Keywords: curricular effectiveness, math curricula, non-experimental methods, matching methods, education policy
WP 09-10
The Social Cost of Open Enrollment as a School Choice Policy
Cory Koedel, Julian R. Betts, Lorien A. Rice & Andrew C. Zau
We evaluate the integrating and segregating effects of school choice in a large, urban school district. Our findings, based on applications for fall 2001, suggest that open enrollment, a school-choice program that does not have explicit integrative objectives and does not provide busing, segregates students along three socioeconomic dimensions – race/ethnicity, student achievement and parental-education status. Using information on expenditures to promote integration at the district, we back out estimates of the social cost of open enrollment realized in terms of student segregation. Our social-cost estimates range widely depending on the weights that we place on the different dimensions of integration. However, even using conservative valuations of the different integrative measures suggests a social cost at this single district of over 3.4 million dollars (in year-2000 dollars). When considered in the context of the nation as a whole, where open-enrollment programs are commonplace, this estimate from a single district is substantial. However, we also note that there may be benefits not related to integration that counterbalance some or all of these costs.
JEL Codes: I20, J15, R23
Keywords: school choice, open enrollment, integration, segregation, segregation costs
WP 09-06
Postsecondary Education Structure
Originally listed as:Postsecondary Education Structure and Human Capital Production
Cory Koedel
States differ substantially in the structures of their public four-year university systems. This paper uses micro-level data to evaluate the effects of postsecondary education structure on individuals’ educational and labor-market outcomes. Postsecondary education structure affects whether individuals attend universities at all, whether they attend public or private universities, and whether they attend large or small universities. Individuals who are exposed to more-fractionalized structures are adversely affected in the labor market. In conjunction with evidence that it is more expensive to educate students at smaller universities, this latter result suggests that states with more-fractionalized postsecondary education structures should look to consolidate their resources into fewer, larger universities.
JEL Codes: I20, I23, J24
Keywords: postsecondary education structure, higher education structure,
small university, large university, postsecondary education costs
WP 09-02
Does Student Sorting Invalidate Value-Added Models of Teacher Effectiveness? An Extended Analysis of the Rothstein Critique
Cory Koedel & Julian R. Betts
Value-added modeling continues to gain traction as a tool for measuring teacher performance. However, recent research (Rothstein, 2009, forthcoming) questions the validity of the value-added approach by showing that it does not mitigate student-teacher sorting bias (its presumed primary benefit). Our study explores this critique in more detail. Although we find that estimated teacher effects from some value-added models are severely biased, we also show that a sufficiently complex value-added model that evaluates teachers over multiple years reduces the sorting-bias problem to statistical insignificance. One implication of our findings is that data from the first year or two of classroom teaching for novice teachers may be insufficient to make reliable judgments about quality. Overall, our results suggest that in some cases value-added modeling will continue to provide useful information about the effectiveness of educational inputs.
JEL Codes: I20, I28 and I21
Keywords: value added, measurement of teacher quality, outcome-based teacher
quality
WP 08-08
An Empirical Analysis of Teacher Spillover Effects in Secondary School
Cory Koedel
This paper examines whether educational production in secondary school involves joint production among teachers across subjects. In doing so, it also provides insights into the reliability of value-added modeling. Teacher value- added to reading test scores is estimated for four different teacher types: English, math, science and social studies. While the initial results indicate that reading output is jointly produced by math and English teachers, post-estimation falsification tests debunk the math-teacher “effects” - that is, there is in fact no evidence of joint production in secondary school. The results offer a mixed review of the value-added methodology, suggesting that it may be useful in some contexts but not others.
JEL Codes: I20, I22
Keywords: value-added, teacher quality, secondary school teachers, educational production
WP 08-07
Value-Added to What? How a Ceiling in the Testing Instrument Influences Value-Added Estimation
Cory Koedel and Julian Betts
Value-added measures of teacher quality may be sensitive to the quantitative properties of the testing instruments upon which they are based. This paper focuses on the sensitivity of value-added to a particularly relevant testing-instrument property – test-score-ceiling effects. Test-score ceilings are likely to be increasingly common in testing instruments across the country as education policy continues to emphasize proficiency-based reform. Encouragingly, we show that over a wide range of test-score- ceiling severity, teachers’ value-added estimates are only negligibly influenced by ceiling effects. However, as ceiling conditions approach those found in minimum-competency testing environments, value-added results are significantly altered.
JEL Codes: I20, I21 and J24
Keywords: Value Added, Test Score Ceiling, Ceiling Effects, Teacher Quality, Teacher Value Added
WP 07-13
Teacher Quality and Dropout Outcomes in a
Large, Urban School District
Cory Koedel
Recent research shows that variation in teacher quality has large effects on student performance. However, this research is based entirely on student test scores. This paper evaluates teacher quality in terms of another educational outcome of great interest – graduation. Using a unique instrumental variables approach to identify teacher effects, I find that differences in teacher quality have large effects on graduation outcomes. Because teacher effects on graduation outcomes will be more pronounced for students who are on the graduation margin, the results imply an avenue through which high-quality teachers are more productive with disadvantaged students.
JEL Codes: I20, I21 and J24
Keywords: Teacher Quality, Teacher Evaluation, Dropouts, Graduation Outcomes, Multiple Endogenous Treatments
WP 07-08
Re-Examining the Role of Teacher Quality In the Educational Production Function
Cory Koedel & Julian R. Betts
This study uses administrative data linking students and teachers at the classroom level to estimate teacher value-added to student test scores. We find that variation in teacher quality is an important contributor to student achievement – more important than has been implied by previous work. This result is attributable, at least in part, to the lack of a ceiling effect in the testing instrument used to measure teacher quality. We also show that teacher qualifications are almost entirely unable to predict value-added. Motivated by this result, we consider whether it is feasible to incorporate value-added into evaluation or merit pay programs.
JEL Codes: I20, I21, J24
Keywords: teacher quality, educational production, teacher value-added, value-added, test-score ceiling effects, teacher evaluation, teacher accountability, elementary school
WP 07-07
Teacher Quality and Educational Production in Secondary School
Cory Koedel
This study uses administrative data linking students and teachers at the classroom level to evaluate teacher quality and joint production in secondary school. Teacher quality is measured by value-added to student test scores in math and reading. Although empirical research has struggled to link observable teacher qualifications to student achievement, teacher quality measured by student performance varies significantly and has important effects on educational outcomes. I identify which teacher inputs affect which test-score outputs in secondary school and find strong evidence of joint production. The results from this study are applicable to incentive design and teacher accountability.
JEL Codes: I20, I21, J24
Keywords: teacher quality, educational production, joint production, teacher value-added, value-added, teacher evaluation, secondary school
Updated substantially as WP-0808