| Methodology
of 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
was developed in a doctoral Dissertation.(Education
Achievement 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 components 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.
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 correlation,or the connection,between
spending (Per-Pupil Expenditure or PPE) and achievement
in Massachusetts 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 .83.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 (EI)is generated
in the following manner:
Utilize the 1998 MCAS results as
an outcome indicator for achievement in each of the
state's most populous 240 or so districts (the exact
number depends on grade level).(NOTE:This model does
not evaluate results in the smallest communities of
the state,which comprise about 2%of the population.)
Utilize the EI 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.
The basis for this model was developed
as a doctoral dissertation.The following provides detail
on the statistics behind the model that is used to predict
expected scores based on demographics.
Robert D.Gaudet
rgaudet@rcn.com
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