The Impact of Individual Teachers on Student Achievement: Evidence from Panel Data

It has been concluded by many that teacher quality (to students’ achievement) is crucial, however the variation in the quality is influenced by attributes that are difficult to quantify. Though many studies have been made in past, the empirical difficulties for all are primarily data quality related. For example, in studies where teachers were only observed under one class of students, the teacher’s effects and other classroom specific factors can’t be differentiated from each other.
Thus using a set of panel data on student’s test scores not only would allow comparison in the performance of the same student given different teachers, but would also identify variation of teacher quality from variation of students’ abilities and attributes, and from other characteristics/factors (i.e. class size). Moreover, variation in teacher quality is separated from variation in school-level educational inputs, such as principal quality, and also from time-varying factors. One of the results showed that within school there is a large variation in quality among teachers. Another finding indicated that longer teaching experience also significantly raises student test scores.


Background

Data was obtained on two adjacent districts in New Jersey, where the spending per pupil at the district A was slightly above, and district B was slightly below the average. Both districts have multiple elementary schools, with multiple teachers serving each grade within each school.  A single teacher holds the entire class for one day to lecture on reading and math; the teacher is then evaluated through nationally standardized exams (divided into four parts: reading – vocabulary, comprehension; math – computation and concept) given to students


Results

Test score was represented in an equation to be a function of several factors.[1] This equation showed that there was no clear link between current test scores and past inputs apart from those that span across years like the student’s fixed characteristics. Current inputs such as teacher quality are said to have an effect on both current and future student success.

 The result showed that as a predictor, teacher fixed effects is found to be significant in both reading and math subject. Experience is also a significant predictor, except for math concepts. In addition, teacher quality is implied to have a large impact on students’ output.
Note however, that due to the variation in the districts’ capabilities (salaries, amenities, and etc.) in attracting teachers, it is expected that the variation in quality among teachers at broader geographical levels may be larger than the within-school presented in this study.

Conclusion

Even though test scores do not cover all range of student’s learning, it is widely recognized by people of authorities and by the public to be an indicator of one’s achievement.
This study suggests that raising teacher quality is vital in enhancing the student’s performance. On the other hand, in a setting where teacher characteristics are not related to teacher quality, policies focused on giving performance-based reward are found to be more effective than policies giving credential-based incentive.
According to some literature, the principal’s input (opinion) of teacher quality is highly correlated with student test scores. Teacher evaluations which are considered to be an important tool in gauging the teacher quality are also able to reflect what is not seen in the test scores.
The decline in the availability of teachers poses as an additional burden on the effort to improve the quality public school teachers. Another finding is that union wage compression and improved labor market opportunities for highly skilled females had reduced the supply of highly skilled teachers.
The goal now is to focus a study in determining how skilled teachers may be identified, recruited and retained.



Source:
Rockoff, J., “The Impact of Individual Teachers on Student Achievement : Evidence from Panel Data”, American Economic Review, Vol. 94, No. 2, (May, 2004), pp. 247-252.



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