td_calibrate            Calibrate each language group separately
td_dif                  Robust linking, anchor selection and
                        small-sample DIF
td_features             Which item features predict DIF?
td_impact               Does item-level DIF add up to different pass
                        rates?
td_mh                   Mantel-Haenszel DIF with purification
                        (conventional baseline)
td_report               Draft a comparability report
td_simulate             Simulate a source-language and a translated
                        administration with known DIF
