Participants who slept less than 6 h had higher anxiety scores. Because the study was cross-sectional, temporal ordering could not be established, and the findings should not be interpreted as evidence of causation.
因果边界
横断面研究中的“相关”不能被改写为“导致”。
研究范围
特定样本的结果不能被扩大为所有大学生。