Single-case researchers frequently adopt a form of response-guided experimentation where decisions about the design of the study are made based on an ongoing visual analysis. For example, multiple-baseline researchers may delay the start of intervention until data document a stable baseline pattern so that baseline trends can be reliably extended,…

This study examines the relationship between sample size and item parameter estimation precision when utilizing the one-parameter model. Item parameter estimates are examined relative to "true" values by evaluating the decline in root mean squared deviation (RMSD) and the number of outliers as sample size increases. This occurs across…

In the study, a part of longitudinal research focused on the emergence of mathematical knowledge structures in a learner's mind is presented. It concentrates on the analysis of introspective data gained from the author's study of a non-standard arithmetic structure in terms of the model of abstraction in context (Hershkowitz, Schwarz and Dreyfus).…