Differential response time among adults from different age groups on PIAAC literacy items

To build a comprehensive validity argument for inferences about learners, a wide variety of data sources should be used. Response process data can be particularly useful for understanding examinees’ response processes and make inferences about their scores. Data from the Programme for the International Assessment of Adult Competencies (PIAAC) contains the total response time for each item. Drawing on the U.S. PIAAC literacy data set, the purpose of this study was to examine the response process time of adults from different age groups using the differential response time (DRT) procedure. Three research questions were addressed: whether adults of different age groups show different response times on PIAAC literacy items; whether such differences remain after we control for examinees’ literacy ability; and what are the characteristics of items that show differential response time (when overall literacy ability is controlled for). We found a consistent pattern that participants in the older group used more time than those in the younger group when responding to each of the 52 PIAAC literacy items. When the examinees’ total literacy ability was controlled for, the older group spent more time responding to six out of 52 items than the younger group did. We also examined the characteristics of items that showed DRT. Findings from this study could help with interpreting observed differences in PIAAC literacy test scores between older and younger adults. A deeper understanding of adult learners' response process also has important implications for adult literacy assessment strategies.