Adult Reading Skills Assessment: The Development of the Test

According to PIAAC studies, a significant proportion of adults in Poland demonstrate low literacy skills, yet no accessible, standardized tool exists to diagnose these deficits. To address this gap, we developed CZYTEST, an online, self-administered assessment of functional reading comprehension tailored to the lower end of the adult literacy spectrum. We describe the test’s theoretical framework, item construction, and psychometric validation based on a representative sample of Polish adults (N = 400). The assessment utilizes functional texts (e.g., medical leaflets, job ads) with items tackling comprehension and was calibrated using a two-parameter logistic (2PL) Item Response Theory (IRT) model. Results confirmed the tool’s unidimensionality and high reliability (α = .88). Using Gaussian mixture modeling and external criteria (e.g., self-reported reading difficulties), we established empirically derived cutoff scores that effectively distinguish struggling readers from those with functional proficiency. Findings demonstrate that reliable, unproctored online assessment of low-literacy adults is feasible using ungoogleable items. CZYTEST provides a scalable, ecologically valid solution for identifying functional illiteracy in research and practice.