My dissertation research explored responder behaviors (e.g., demonstrating response styles, carelessness, and possessing misconceptions) that compromise psychometric quality and impact the interpretation and use of assessment results. Identifying these behaviors can help researchers understand and minimize their potentially construct-irrelevant impact on the psychometric quality of measurement procedures. In three studies related to response quality, we analyzed item response data in terms of subgroups and in terms of missingness levels respectively to evaluate the sensitivity of item response theory (IRT) indicators to response characteristics that can compromise psychometric quality; we also validated a diagnostic classification model (DCM) aiming to diagnose the presence of misconceptions. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]