Progressive Achievement scales are interval scales.
Students test results sit upon the scales representing their performance on a progressive achievement test and inferring their level of attainment in a particular learning area.
When students complete different tests, comparing the number of different responses cannot tell us anything about their relative or actual achievement in a learning area.
Correct responses from different tests in the same learning area need to be transformed into scale scores if we want to compare achievement.
Every Progressive Achievement learning area is aligned to a common scale, these include the PAT Maths scale, the PAT Reading scale, and many others.
Just as we can use a thermometer to measure and the Celsius scale to express differences in temperature, we can use Progressive Achievement Tests (PAT) to measure and the described scale to understand student’s overall abilities in a learning area.
The higher the students scale score the greater the estimated ability in that learning area.
Importantly, two students achieving approximately the same scale score in a learning area have demonstrated similar ability and understanding, regardless of the year level or the test items they responded to.
It is important to note that scale scores cannot be compared between different learning areas, such as maths and reading.
Common achievement scales make it possible to compare individual and group performance at a point in time, as well as to monitor progress in learning by tracking changes in scale scores overtime for individuals and groups.
Progressive Achievement Scales act as road maps that allow us to understand where every student is in their learning progress.
The described scales contextualise the skills, knowledge and understanding they have demonstrated. They also allow us to meet them at their points of need and to measure their progress overtime.