15. 知识点：Misclassifying Operating Expenses as Nonrecurring or Nonoperating ；Core operating margin=(sales-COGS-SG&A)/sales ；Analysts should compare changes in the core operating margin over time and look for negative nonrecurring or nonoperating items that occurred when the ratio increased. This may be the result of misclassifying an operating expense. ；如果本年CGM较小，且有大的负项，这是Warning Sign，因为第二年有可能将负项作为No-recurring Expense，以提高CGM；为了准确度量CGM，有的时候会做回归分析，以找到较稳定的CGM。；A warning sign that ordinary expenses are now being classified as nonrecurring or nonoperating expenses is falling core operating margin followed by a spike in negative special items. 参见：金程教育2013年CFA二级“中国梦”系列──CFA II NO.7考前押题
