TY  - JOUR
AU  - Koedel,Cory
AU  - Betts,Julian
TI  - Value-Added to What?  How a Ceiling in the Testing Instrument Influences Value-Added Estimation
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 14778
PY  - 2009
Y2  - March 2009
UR  - http://www.nber.org/papers/w14778
L1  - http://www.nber.org/papers/w14778.pdf
N1  - Author contact info:
Cory Koedel
Dept. of Economics
University of Missouri
118 Professional Building
Columbia, MO  65211
E-Mail: koedelc@missouri.edu

Julian Betts
Department of Economics, 0508
University of California, San Diego
9500 Gilman Drive
La Jolla, CA 92093-0508
Tel: 858/534-3369
Fax: 858/534-7040
E-Mail: jbetts@ucsd.edu
AB  - Value-added measures of teacher quality may be sensitive to the quantitative properties of the student tests upon which they are based.  This paper focuses on the sensitivity of value-added to test-score-ceiling effects.  Test-score ceilings are 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.  We suggest a simple statistical check for ceiling effects.
ER  -