Part I Designing the User Study -- Overview -- Variables -- Design equation and statistics -- Between-subjects design -- Within-subject designs -- Advanced designs -- Part II Practical Tips -- Understanding main and interaction effects -- Conducting multiple comparisons -- Gold standard and user evaluations -- Recruiting and motivating study participants -- Institutional review board (IRB) approval -- Resources -- Part III Common Mistakes to Avoid -- Avoid bias -- Avoid missing the effect -- Avoid missing variables or conditions -- Other errors to avoid -- Appendix: cookbook for designing user studies in informatics.