Optimal Two-Stage Designs for Ordered Categorical Outcomes

Functions to design and simulate optimal two-stage randomized controlled trials (RCTs) with ordered categorical outcomes, using rank-based tests and interim decision rules for futility and superiority, following Park (2025) . The functions 'rule()', 'op()' and 'design_table()' provide a single entry point for constructing designs, evaluating their operating characteristics, and tabulating several designs at once. The separate functions provided for each combination of test statistic and stopping rule up to version 1.0.2 were deprecated in 1.0.3 and are removed here. Please see the package reference manual and the vignette for details.