The psychologist Peter Gollwitzer of the University of Konstanz studies how plans help people reach their goals. His best-known idea is the implementation intention, in German a Wenn-dann-Plan, an if-then plan. It decides in advance: if situation Y arises, then I will do X. In 2006, Gollwitzer and Paschal Sheeran analyzed 94 independent tests. If-then plans had a positive effect of medium to large size on reaching goals. In a university news article of 2019, Gollwitzer was quoted as saying that people normally reach 20 to 30 percent of their goals, and 60 to 70 percent when they plan how they will reach them.