Best-Fit Line
Core Sentence / 核心句
A best-fit line represents the overall data trend, with residuals distributed reasonably on both sides.
Procedure / 步骤
Label axes and units, choose a useful scale, plot points, draw one trend line, then calculate slope using two well-separated points on that line.
Watch Out / 易错点
不要逐点连线、强制穿原点或只用相邻原始点求 slope。