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APPENDIX B: Deriving the Effectiveness
Index
The Effectiveness Index (EI) is derived
by comparing actual scores on standardized tests with
scores as predicted by a model which factors in the
role community characteristics play in educational outcomes.
The Community Effects Factor (CEF)
model, the statistical basis for the Effectiveness Index,
was developed in a doctoral dissertation (EducationAchievement
Communities: A New Model for "Kind of Community" in
Massachusetts Based on an Analysis of Community Characteristics
Affecting Educational Outcomes, May 1998, University
of Massachusetts, Amherst). That work is the basis for
determining school effectiveness. The model examines
the relationship between selected demographic characteristics
and educational outcomes. These characteristics include:
average education level, average income, poverty rate,
single-parent status, language spoken, and percentage
of school-age population enrolled in private schools.
These variables were chosen because they correlate with
achievement and because the education literature identifies
them as connected to academic performance.
In order to refine a better CEF model,
it is first necessary to factor the impact of these
demographic variables on each other. This can be done
through a technique known as principal component analysis
that is a statistical mechanism that reduces many variables
to a few salient ones that have the most impact on an
outcome. Once the factors have been identified, a regression
analysis produces the equations that can be used to
either build a kind-of-community model or to predict
expected district performance on achievement tests.
The degree to which a community's characteristics lifts
or lowers test scores is reflected in a Community Effects
Factor (CEF), a measure of demography.
The CEF, which is a measure of the
demographic lift or drag of each community concerning
educational achievement, is a good point of departure
for analyzing school and school district effectiveness.
The CEF identifies expected levels of performance based
on community characteristics which, for better or worse,
are very powerful indicators of educational achievement
in Massachusetts. In this analysis, Weston is the most
demographically advantaged community in the state in
terms of educational outcomes (CEF = + 2.8), and Lawrence
is the least advantaged (CEF = - 4.8). The CEF has a
strong relationship, or correlation, to test scores.
In practical application, the CEF establishes the methodology
for predicting likely standardized test scores based
on district demography.
Correlation is a process that identifies
the interdependence of one variable with another. Correlation
simply shows "the extent to which two things typically
run together." [The Economist, 6 Dec. 1997, p. 82].
Correlation is not equivalent to causation; it can only
reveal tendencies between variables, not identify causes.
Correlations simply demonstrate relationships. A perfect
correlation would be 1.0. For example, the correlation
between inches and feet is 1.0 because it is a perfect
linear fit; 12 inches always equals one foot. Correlations
in real world situations involving human behavior are
never 1.0.
The dissertation research found that
the correlation, or the connection, between spending
(Per-Pupil Expenditure or PPE) and achievement in Massachusetts
was .28, which is relatively low. While spending clearly
matters, merely increasing spending levels has a relatively
weak impact on results. Increasingly, many people are
coming to the realization that how a system spends money
is more important than how much money it spends. The
achievement outcome accounted for by the community effects
factor (CEF) is much stronger; that relationship is
.85. This is not to say the community context, the CEF,
is the most important determinant of school success,
but it is a significant element that must be a major
consideration in any plan to improve education in disadvantaged
areas.
The Effectiveness Index was generated
in the following manner:
• Utilize the 1999 MCAS results
as an outcome indicator for achievement in each of the
state's most populous 200 communities. (NOTE: This model
does not evaluate results in the smallest communities
of the state which comprise about 3% of the population.)
• Utilize the CEF model to predict
a score for each district. This predicted score is based
solely on community characteristic as they affect educational
outcomes.
• Compare the actual to the predicted
score. Systems whose actual scores are significantly
higher than predicted scores and whose absolute scores
are at or above state average are identified as effective.
Systems with positive effectiveness indexes but scores
below state average are identified as noteworthy.
For more information, please contact
the UMass Donahue Institute, (617) 287-7055 or contact
Robert Gaudet, (617) 469-6843; rgaudet@rcn.com.
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