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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 English-language arts compared to grade two English-language 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.

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 grade-to-grade. 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 cross-sectional comparison, third-grade 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.

California Department of Education