SCALE CREATION

The STEP achievement scales were created using plausible values drawn from a posteriori distribution by combining the item response theory (IRT) scaling of the cognitive items with a latent regression model using information from the background questionnaire. Each respondent was assigned 10 plausible values in each of the achievement scales.

LIST OF ACHIEVEMENT SCALES

The STEP scale scores have the same range, and the description of the underlying skills along the scale is the same, as for PIAAC. The literacy proficiency was modeled using IRT, in a scale that ranges from 0 to 500.

The 500-point scale is divided into 6 levels, each referring to a level of proficiency in terms of the tasks that an individual should be able to do at that point on the scale:

• Below level 1 (0–175)
• Level 1 (176–225)
• Level 2 ( 226–275)
• Level 3 (276–325)
• Level 4 (326–375)
• Level 5 (376–500)