Pulling Back the Curtain: The Relationship Between Cumulative Teacher Quality and Students' Educational Outcomes

• In Event: Promising Scholarship in Education: Dissertation Fellows and Their Research

Abstract

Research over the past thirty years has repeatedly shown that the quality of a teacher is the most important schooling factor impacting student achievement, and educational policy, in turn, has reflected this assessment, both by allocating substantial resources to improving and assessing teacher quality. Yet in spite of this broad consensus, we have yet to identify which proxies of teacher quality best predict desired outcomes. Moreover, though there is a growing recognition that the effects of teacher quality may emerge slowly or be visible only with time, little attention has been paid to students’ long-term outcomes, such as postsecondary degree attainment. Therefore, in order to gain a better sense of how different indicators of teacher quality represent and impact students’ educational success, this study examines the relationship between two dominant measures of teacher quality, teacher qualification (measured by years of experience, advanced degree, and subject matter expertise) and teacher effectiveness (measured by value-added modeling), in terms of their influence on students’ short-term academic growth and longterm educational success (measured by completion of a college degree). Since students are exposed to teachers of varying quality over the course of their schooling and achievement is closely related to that cumulative exposure, this study computes cumulative teacher quality indices that are able to more precisely estimate the impact of teacher quality.

Study Design & Methods
To fully understand the impact of teacher quality, this study utilizes data from the 20-year record of the Longitudinal Study of American Youth (LSAY), a national probability sample funded by the National Science Foundation. It is the only national dataset to include annual measures of students’ mathematics and science achievement alongside teacher information, allowing for a calculation of the cumulative impact of teacher effectiveness and qualification. Additionally, the two stages of data, which look across almost two decades, allow for a more accurate and comprehensive evaluation of the impact of teacher quality on students’ long-term outcomes. This study seeks to isolate the effect of teacher quality by controlling for differences between schools by using a fixed effects model. Moreover, the present study controls for a variety of factors in considering the measures of its analytic models and used multiple imputation methods to handle missing observation in the data.
To examine the relationship between cumulative teacher quality and student’ educational success, this study used student’s 12th grade standardized test score for short term achievement through fixed effect regression. The study used dichotomous dependent variables (whether students earned a bachelor degree or not) for long term educational success through fixed effects logistic regression.

Findings & Implications
The present study documents that being taught by a consecutive number of high quality teachers significantly increases the odds that a student will have higher achievement and attain bachelor’s degree, a finding that aligns with limited previous research on the enduring effect of teachers on their students. Specifically, the study found that cumulative teacher effectiveness and all three cumulative teacher qualification indices were shown to have a significant positive association with students’ achievement in both math and science (See Table 1). Also, cumulative teacher quality indices were found to have an overall positive relationship with students’ college graduation. Among the proxies of teacher quality used in this study, cumulative teachers’ level of education in mathematics appears to be the only one that was insignificant (See Table 2). The study does not intend to say that we should either go back to teacher qualification measures or focus only on teacher effectiveness when measuring teacher quality. Rather, it argues that neither one can be used in isolation to measure a given teacher’s quality. Therefore, instead of measuring teacher quality using a single proxy or measuring one’s quality using crosssectional data, educational leaders and researchers might consider measuring teacher quality in a more comprehensive and cumulative manner, which includes a balance between teacher qualification and teacher effectiveness.

Author

• Se Woong Lee, University of Wisconsin - Madison