The method of propositional manipulation (MPM) aims to help students develop conceptual understanding of statistics by guiding them into self-explaining propositions. To explore task- and student-related factors influencing students' ability to learn from MPM, twenty undergraduate students performed six learning tasks while thinking aloud. The results indicate that whether students learn from MPM depends on their statistics proficiency level, the subject matter, the number of propositions in the learning task, and the instructions. MPM learning tasks should be tailored to the students' level of expertise and students should be instructed more than once to integrate all propositions in the learning task into their arguments. (Contains 4 tables.)