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Comparing California Standards Test (CST) Results
When comparing results for the CSTs, compare results only within the same
subject and grade. That is, grade two Englishlanguage arts compared to grade
two Englishlanguage arts or grade six mathematics compared to grade six
mathematics. No direct comparisons should be made between grades or between
content areas.
Two types of comparisons are possible: 1) comparing the average scaled score or
2) comparing the percentage of students scoring at each performance level. The
reviewer may compare results for the same grade and subject across years within
a school, between schools, or between a school and its district, county, or the
state. When making comparisons, the reviewer should consider comparing the
percentage of students scoring proficient and advanced, since the state target
is for all students to score at or above proficient.
Comparisons may also be made by calculating the overall percentage of students
within a school who scored proficient and advanced and comparing this to the
overall percentage of students in another school, the district, the county, or
the state who scored proficient or advanced. To do this first calculate the
number of students who scored proficient and advanced for the subject area at
each grade level ([%PRO + %ADV] x number tested for the grade and subject area
= No. scored PRO/ADV). Then add the No. scored PRO/ADV for all grades and
divide by the total enrollment.
Comparing California Achievement Tests, Sixth Edition Survey (CAT/6
Survey) Results
Comparing Group Test Results
Since the CAT/6 Survey is unchanged from year to year and was administered in
all California public schools, reviewers may compare the test results from year
to year as well as between and among schools and/or districts for the tests
administered during spring 2003 and spring 2004. The most defensible comparison
is the Percent of Students Scoring At or Above the 50th NPR. This is the
percentage of students in the group purported to have demonstrated achievement
at or above grade level on each specific test. A number of comparisons are
possible, each with its own set of cautions.
Same Year, Within School Comparisons
A reviewer may want to compare the performance of students at different grade
levels within a school. Similarities and differences in student performance in
the same subject may be seen by comparing the Percent of Students Scoring At or
Above the 50th NPR for each grade. When making this comparison, it is important
to remember that the number of students in each group affects the confidence of
the inferences that can be made. The smaller the group the more cautious one
should be in making comparisons. It is also important to note that the national
norm groups to which California's students' scores are compared were unique for
each grade level.
Same School, Different Years Comparisons
There are two ways to compare two years of data for the same school. One can
look at a cohort comparison over time by following a group of students from
gradetograde. For example, if 48% of a school's third graders scored at or
above the 50th NPR in 2003 and 51% of the fourth graders scored at or above the
50th NPR in 2004, the school appears to be effective in working with this group
of students. When making this comparison, it is important to understand that
even if the number of students is the same from year to year, the group's
composition may be quite different if student mobility (transiency) is high.
In a crosssectional comparison, thirdgrade results are compared from year to
year. Since the results for two separate groups of students are being compared,
differences that may exist between the two groups should be considered.
Scale Score Comparisons (Cohort)
While scale scores cannot be compared between different tests or subject areas,
scale scores are useful for comparing performance over time on the same test
for the CAT/6 Survey. For example, if the second grade in a school had 52% of
the students score at or above the 50th percentile and 52% of the students also
scored at or above the 50th percentile in third grade, a comparison of the
average scale scores may be used to determine if the students actually
demonstrated growth during the year. If a group maintains the same position
relative to the norm group, the average scale score will increase because the
average scale scores for the norm groups increase from grade to grade.
Comparing CAT/6 Survey Results with Stanford 9 Results
Reviewers should make no direct comparisons between the 2004 CAT/6 Survey
results and the Stanford Achievement Test, Ninth Edition (Stanford 9) results
from 1998 through 2002 that are posted on the Internet. Different publishers
developed the two test series, and the CAT/6 Survey tests were developed and
normed more than five years after the Stanford 9. Making direct comparisons
between the results for the two test series is inappropriate because they have
different formats and difficulty levels.
