Deciding to Stop Early or Continue the Experiment After Checking <italic>p</italic>-Values at Interim Points: Introducing Group Sequential Designs to UI-Based Comparative Studies.

AbstractNull hypothesis significance testing (NHST) is widely used in the field of human-computer interaction (HCI), and caution has been advised against deciding whether to stop or continue an experiment based on checking <italic>p</italic>-values. However, in clinical trials, NHST with interim analysis is commonly employed by adjusting the <italic>α</italic> levels to control Type I error rates. This approach, known as a group sequential design, can also be beneficial in the HCI field. We analyzed existing datasets of target-pointing tasks using group sequential designs and experimentally demonstrated that, depending on the <italic>α</italic>-level correction method, we could reduce the number of participants by 40.4–56.5%. Therefore, employing group sequential designs enables significant time and cost savings for both participants and researchers in the HCI field. [ABSTRACT FROM AUTHOR]