预期进球
xG
基于历史数据，估计某类射门转化为进球的概率模型。
短标签已本地化。完整定义段落为准确性保留英文。
定义
Expected goals (xG) assigns a probability to a shot based on features such as location, angle, body part, and sometimes pressure or assist type. An xG of 0.25 means similar historical shots become goals about one time in four — not that this specific shot “should” score.
xG is strongest as a process descriptor over samples and weakest as a single-match courtroom verdict. Models differ by vendor; small samples are noisy; build-up quality before the shot is only partly visible in many public models.
注意
不要将单场比赛中的xG优势视为谁应得胜利的证据。点球阶段应与开放比赛过程数据分开处理。