Misconception: PVAAS should always indicate growth if the percentage of students scoring Proficient or above increased since last year.
Comparing the percentage of students who score Proficient (or above) over time does not account for changes in achievement within performance level categories. Comparing the proficiency rate at a district or school over time does not account for changes in the cohort of students included in the rate. PVAAS value-added reporting follows the progress of individual students (as a part of a group of students) over time, regardless of their achievement level, to ensure that all students count.
PVAAS in Theory
Imagine the scenario below. The Mathematics achievement level of Student 1 is represented by the line with the blue diamonds, and that of Student 2 is represented by the line with the red squares. The orange, purple, and green lines show the percentile corresponding to the Basic, Proficient and Advanced performance levels. The achievement level of Student 1 has steadily increased over time while the achievement level of Student 2 has steadily decreased over time. From seventh to eighth grade, Student 1 moved from the Basic to Proficient performance category. From seventh to eighth grade, Student 2 maintained his position in the Proficient performance category although his achievement level has gone down.
STUDENT TESTING HISTORY IN PSSA MATHEMATICS FOR STUDENT 1 AND STUDENT 2
By considering the number of students who have scored Proficient and assuming all other students have maintained the same performance categories, the number of students has increased with the addition of Student 1. However, this does not consider that Student 2's achievement level is steadily decreasing over time. A subtler approach is required that considers the growth of all students regardless of their achievement level.
PVAAS does not provide a measure of growth for individual students, only for groups of students.
PVAAS in Practice
PVAAS does not measure students' growth based on the number or percentage of students who tested Below Basic, Basic, Proficient, or Advanced, as compared to previous years. PVAAS detects these subtle changes in progress even within performance levels. As a result, educators are recognized when they make growth with students at/above proficiency and below proficiency. This can be very encouraging to LEAs/districts, schools and teachers serving low-achieving students, who might not otherwise be recognized for their students' growth.