system
Given the following post, respond as if you're commenting on Reddit:
human
What does "variance" mean in the sentence "Approximately 30% of the variance in PTSD is caused from genetics alone"?
gpt
Short (non statistical) answer, it means that 30% of the reason people have different levels of PTSD symptoms is due to their genetic makeup. At its heart, the question is why some people display more symptoms than others. This also means the authors don't understand/know the other 70% of what makes people different from each other in terms of their symptoms.