National Board Certification and Teacher Effectiveness: Evidence From Washington State

ABSTRACTWe study the effectiveness of teachers certified by the National Board for Professional Teaching Standards (NBPTS) in Washington State, which has one of the largest populations of National Board-Certified Teachers (NBCTs) in the nation. Based on value-added models in math and reading, we find that NBPTS-certified teachers are about 0.01–0.05 student standard deviations more effective than non-NBCTS with similar levels of experience. Certification effects vary by subject, grade level, and certification type, with greater effects for middle school math certificates. We find mixed evidence that teachers who pass the assessment are more effective than those who fail, but that the underlying NBPTS assessment score predicts student achievement.KEYWORDS: teacher effectivenessNational Board for Professional Teaching Standardsteacher evaluation AcknowledgmentsWe thank Joe Doctor and the Washington Office of the Superintendent of Public Instruction (OSPI) for helpful comments and Christopher Tien for the expert research assistance he provided. We also thank OSPI and the National Board for Professional Teaching Standards for providing the data used in this study. Any and all errors are solely the responsibility of the study's authors, and the views expressed are those of the authors and should not be attributed to their institutions, the study's funders, or the agencies supplying the data.EDITORSThis article was reviewed and accepted under the editorship of Carol McDonald Connor and Spyros Konstantopoulos.FundingThis study was funded by the Bill and Melinda Gates Foundation and by the National Center for Analysis of Longitudinal Data in Education Research (CALDER), funded through grant #R305A060018 to the American Institutes for Research from the Institutes of Education Sciences, U.S. Department of Education. We thank both funders for their generous financial support.Notes1 Harris and Sass (Citation2009), who break out NBCTs by their licensure cohort and include some cohorts licensed under both the first and second generation of assessments, find some evidence of differential effects by cohort. Chingos and Peterson (Citation2011) study teacher credentials in Florida between 2002 and 2009, but do not explicitly break out NBPTS credentials by certification type.2 As of 2010, 39 states accept the NBPTS credential as a means of fulfilling state licensing or continuing education requirements (Exstrom, Citation2011).3 On the other hand, they consistently find that future NBCTs are more effective than teachers who never become certified.4 Throughout this article, we refer to school years by the calendar year of the spring term.5 The Challenging Schools Bonus pays teachers a maximum of $5,000 and is prorated by the amount of time a teacher spends in an eligible school.6 Washington revised its certification process in 2000 and accepts the National Board certificate as a substitute for the requirements for the "Professional" teaching certificate, which requires teachers to complete a portfolio assessment.7 We matched 94% of NBCT candidates working in public schools using full name and date of birth and an additional 4% using last or maiden name, first initial, and date of birth. Minor misspellings of names in the S-275 data are not uncommon; we additionally matched by hand another 1% of candidates using names, dates of birth, and schools of employment.8 That is, when we break out certificates by type, we only consider teachers certified under the second generation assessment who received certificates between 2002 and 2013. Therefore, some teachers with "other" certificates possess an earlier version of the same certificate. Given the small number of teachers certified in Washington before 2002, this does not encompass many teachers.9 Some of the data related to students and teachers used in this study are linked using the statewide assessment's "teacher of record assignment," a.k.a. assessment proctor, for each student to derive the student's "teacher." The assessment proctor is not intended to and does not necessarily identify the sole teacher or the teacher of all subject areas for a student. The "proctor name" might be another classroom teacher, teacher specialist, or administrator. For the 2009–2010 school year, we are able to check the accuracy of these proctor matches using the state's new Comprehensive Education Data and Research System (CEDARS) that matches students to teachers through a unique course ID. Using the restrictions described above, our proctor match agrees with the student's teacher in the CEDARS system for about 95% of students in both math and reading.10 Because some schools in Washington State use self-contained classrooms in Grade 6, we split the sample based on the class type rather than the grade level. Both elementary and middle school samples therefore include some students in sixth grade.11 Using district-level data that permits better identification of discrete classrooms, Johnson, Lipscomb, and Gill (Citation2015) find that teacher value-added models that rely on teacher–year means of control variables produce teacher effects estimates with correlations of between 0.93 and 0.98 with models using classroom means.12 Our chi-square tests include indicators for whether the student scored above the median on each of the state standardized tests from the prior year; whether the student is female; whether the student is White; whether the student participates in gifted programs; whether the student participates in ELL programs; and whether the student participates in special education programs.13 Clotfelter et al. (Citation2006) pool estimates to the school level using classrooms in Grades 3–5 in one school year. As they point out, the chi-square test may lack power to detect if schools do in fact sort students. To test whether we are actually identifying cohorts with balanced classrooms, we regress the baseline student characteristics on cohort and classroom fixed effects in the restricted sample and test the joint significance of the classroom fixed effects. Using a p value of 0.10 in the chi-square tests to determine nonrandom assignment, we find that none of the models rejects the null hypothesis of no classroom effects at any conventional level.14 Jackson (Citation2014) uses a finer designation of tracks at the high school level by using groups of students who take the same courses. Because our data set does not permit the identification of individual courses at the middle school level, we follow Protik et al. (Citation2013) and use indicators for course type to identify tracks. In our data, we identify a track as a unique combination of school, grade, school year, honors status, and remedial status. Honors and remedial courses are not identified at the elementary school level.15 Because they implicitly limit comparisons of NBCTs to teachers within the same school and grade, models with cohort effects may be conservative estimates if there are differences in true teacher effectiveness across schools.16 An alternative explanation for the difference between NBCT effects at the middle and elementary school level is that later cohorts of NBCTs are more effective than earlier cohorts and the middle school effect is a composition effect caused by the different coverage of elementary and middle school classrooms. To rule out this explanation, we reestimate the elementary regressions using only data from 2010 and later and find very similar results. Results are available from the authors upon request.17 An open question is whether participation in the National Board process improves teacher practice. We additionally estimate models that include teacher fixed effects and a censored experience profile at 10 years to test whether participation in the National Board process improves teacher value-added. We find small within-teacher differences in effectiveness that are not statistically significant. These results are consistent with most of the prior results using student test score data and specifications with teacher fixed effects (Chingos & Peterson, Citation2011; Goldhaber & Anthony, Citation2007; Harris & Sass, Citation2009). Results are available from the authors upon request.18 At the elementary school level, 4.9% of students have an NBCT who earned certification on the first attempt and 1.7% have an NBCT who earned certification on a retake. At the middle school level these numbers are 8.1% and 2.6% for math and 9.9% and 3.0% for reading.19 Note that these are two-sided tests. For models with cohort fixed effects, the F statistic for the test of the equality of the coefficients is F = 11.4 (p < 0.01) for elementary math, F = 3.7 (p = 0.05) for elementary reading, and F = 2.8 (p = 0.09) for middle school reading. When we stack data across elementary and middle schools, we reject the hypothesis that the two groups are equally effective at the 5% level in both math (F = 9.7; p < 0.01) and reading (F = 5.9; p = 0.02).20 The F statistic from the test of equality of the coefficients is F = 1.5 (p = 0.22) for middle school math.21 We convert gains on standardized tests to weeks or months of learning by averaging the results of Bloom et al. (Citation2008) over the relevant grade range and assuming a 36-week school year. These results suggest annual learning gains of 0.50 and 0.36 standard deviations for elementary math and reading, respectively, and 0.34 and 0.27 standard deviations for middle school math and reading, respectively.22 Specifically, we control for teacher-by-track fixed effects, which may not uniquely identify classrooms in middle schools (Johnson et al., Citation2015).23 An additional concern is whether to include teachers who have not submitted assessment results. Some studies have included all teachers with indicators for having submitted an assessment. This may improve efficiency for the student- and classroom-level regressors, but point estimates are generally biased if assessment results are correlated with student and classroom characteristics (Jones, Citation1996). We therefore limit our sample to teachers with assessment outcomes.24 In the Washington data, we observe a 60% first-time pass rate and an 83% three-year pass rate. These numbers are higher than those reported nationally (Hakel, Koenig, & Elliott, Citation2008). However, among a sample of North Carolina teachers, which is another state with a large population of NBCTs, Goldhaber and Hansen (Citation2009) find a first-time passing rate of 54% and an eventual passing rate of about 75%, which are roughly consistent with the patterns we observe. In the analytical samples, the pass rates are even higher: 65%–75% for initial applicants and 85%–95% overall.25 This conversion uses the findings from Bloom et al. (Citation2008) and is discussed in footnote 21.26 We standardize all NBPTS assessment scores against the distribution of first-time assessment results across all certificates.27 The differences in average effectiveness are not statistically significant in either subject.