Programme for the International Assessment of Adult Competencies (PIAAC) 2023 - Skills Use and Social Outcomes

PIAAC Survey Results

This chapter outlines the methodological elements of the PIAAC survey that are focused on how skills are measured and reported in this release.

Skills Use Indices

In addition to assessing proficiency, PIAAC collected detailed information on how frequently adults used various skills in their work and daily lives. To support meaningful analysis, responses to these behavioural questions were combined into standardised indices using Item Response Theory (IRT). Each index aggregated multiple items that reflected the use of a particular skill (e.g. reading at work), resulting in standardised indices developed through IRT. Each index combined responses to multiple survey items into standardised scores, the resulting scales were continuous variables, standardised to have a mean of 2 and a standard deviation of 1 across the pooled sample of respondents in all participating countries and economies. Higher scores indicated more frequent use of the skill.

Indices were available for a range of skill areas, including:

• Reading, writing, numeracy, and Information & Communication Technology (ICT) (both at work and at home)
• Influencing others, task discretion, learning at work
• Problem solving and complex problem solving
• Physical work

Each index was based on responses to a specific set of questions (listed in the Background Notes) and allowed for comparative analysis by age, education, gender, and economic sector.

Scale Scores – Measuring Proficiency

Proficiency in literacy, numeracy, and adaptive problem solving (APS) were assessed directly through performance tasks completed by survey respondents. These responses were analysed using IRT methodology, which adjusts for differences in test item difficulty and provides each respondent with a scale score between 0 and 500. These scores represented the individual's estimated proficiency, even if they did not complete all test items.

The results are presented in two main forms:

• Mean scale scores – estimates of average proficiency for the overall population and specific subgroups
• Proficiency levels – categories aligned with specific score ranges, representing progressively more complex tasks

The literacy and numeracy domains are divided into five levels, while the APS domain is divided into four. These levels are used to describe both the overall distribution of skills and differences across demographic groups.

Comparability with PIAAC Round 1

While the core assessment frameworks and many survey questions remained consistent between PIAAC Round 1 (2012) and Round 2 (2022/2023), some updates were introduced to reflect changes in the labour market and digital technology. As such, direct comparisons across cycles should be made with caution.