Touchstone2offers a direct-manipulation interface for gener-ating and examining trade-offs in experiment designs. Basedon interviews with experienced researchers, we developedan interactive environment for manipulating experimentdesign parameters, revealing patterns in trial tables, and esti-mating and comparing statistical power. We also developedTSL, a declarative language that precisely represents experi-ment designs. In two studies, experienced HCI researcherssuccessfully usedTouchstone2to evaluate design trade-offsand calculate how many participants are required for par-ticular effect sizes. We discussTouchstone2’s benefits andlimitations, as well as directions for future research.