Creativity is often needed in requirements elicitation, i.e., generating ideas for requirements, and therefore, techniques to enhance creativity are believed to be useful. [Objective] How does the size of a group using the Power-Only EPMcreate (POEPMcreate) creativity enhancement technique affect the group's and each member of the group's effectiveness in generating requirement ideas? [Method] This paper describes an experiment in which individuals and two-person and four-person groups used POEPMcreate to generate ideas for requirements for enhancing a high school's public Web site.[Results] The data of this experiment combined with the data of two previous experiments involving two-person and four-person groups using POEPMcreate show that, similar to what has been observed for brainstorming, the size of a group using POEPMcreate does affect the number of raw and new requirement ideas generated by the group and by the average member of the group. [Conclusions] The data allow concluding that a two-person group using POEPMcreate generates more raw and new requirement ideas, both per group and per group member or individual, than does a four-person group and than does an individual. This conclusion is partially corroborated by qualitative data gathered from a survey of professional business or requirements analysts about group sizes and creativity enhancement techniques.See the section titled "Compliance with Ethical Standards", just before the references, for a statement about previous publication of parts of this paper's contents.