Abstract Decisions about medical treatments and the setting of health programs involve both technical and value judgments. An important one is evaluating potential tradeoffs between quality of life and length of life or between different domains of quality of life resulting from different treatment options. The time trade‐off TTO) technique is one of the methods used for that purpose. Its most prominent use is in generating the preference weights to be used in the QALY (quality adjusted life years) calculation. In this section, we briefly describe the technique and its underlying assumptions.