Compass Math Test Validity March 2011

1. Compass Math Test Validity March 2011 Mike Orkin, Jo Ann Phillips, Hui Zhang Office of Institutional Research Peralta Community College District

2. Compass Math Test • Peralta students take assessment tests for placement into Math, ESL, and English courses. • Course placement based on test scores is recommended not mandatory. • A student may take courses without taking placement tests.

3. Compass Math Test • Peralta uses the ACT Compass test for math placement. • When students take Compass, they advance through “subtests” until they reach a “placement domain.” • The higher the placement domain, the higher the difficulty level of the recommended courses.

4. Data • Students taking Compass-designated math courses in F08, S09, F09, S10. • Took Compass test immediately preceding semester when they took math course, or • Never took Compass test prior to semester when they took math course.

5. Data Totals • 12,657 student enrollments. • 4,915 (39%) took Compass test. • 7,742 (61%) did not.

6. Data by Placement Domain Courses

7. Placement Domains and Courses • MPRAL – Prealgebra • Arithmetic – Math 250 (0-32) • Pre-Algebra – Math 253 (33-39) • Elementary Algebra – Math 201 (40-100)

8. Placement Domains (Subtests) • MALGE – Algebra. • Elementary Algebra – Math 201 (0-34) • Intermediate Algebra – Math 203 (35-49) • Statistics – Math 13 (50-100)

9. Placement Domains (Subtests) • MTRIG – Trigonometry. • Trigonometry – Math 50 (0-45) • Pre Calculus – Math 1 (46-100)

10. Placement Domains (Subtests) • MCOAL – College Algebra. • Statistics – Math 13 (0-34) • Pre Calculus – Math 1 (35-49) • Calculus – Math 3A (50-100)

11. Compliance Within Placement Domain • Most complied with cutoff score assignment within their placement domain.

12. Compliance Within Placement Domain

13. Validity • A test is “valid” if it measures what it’s supposed to measure. • We looked at this in two ways: • Are grades and success positively related to Compass scores? • Does Compass do “better” than students who don’t take Compass?

14. Validity • Are grades positively related to Compass scores? • On average, as grades increase, so do scores.

15. Validity ANOVA - Assessment test averages by grade.

16. Validity Grade Counts

17. Validity • Do assessment test scores predict a student’s chance of success (C or better) in a course? • Logistic regression estimates the probability of success for a given assessment test score. • For all subtests, as scores get higher, the predicted chance of success increases, indicating predictive validity.

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23. Validity • Does Compass do better than students who don’t take the test? • Assume that those who don’t take Compass essentially select a class at random.

24. Validity • For non-Compass students, just by chance, some strong students will take lowest-level courses (too easy) and some weak students will take higher level courses (too difficult). • If Compass is properly assessing students, only weaker students will take lowest level courses and stronger students will take higher level courses.

25. Validity • Thus, students who take Compass should do worse than those who don’t at lowest subtest and better than those who don’t at higher levels. • This is exactly what we observe in the data.

26. Validity Chi Square - Success – Compass Test v. No Test

27. Validity • Similar result when comparing grades of students who take Compass with those who don’t.

28. Validity ANOVA - Test v. No Test Course GPA

29. Summary • All four methods of analysis yield statistically significant results supporting Compass validity.

30. Summary • On average, as grades increase, so do Compass scores. • As Compass scores increase, the predicted chance of success increases. • Students who take Compass do better than those who don’t in the higher subtests and worse in the lowest subtest, in both course success and grades.