Python 财务异常检测：统计离群点自动筛查

{"type":"doc","content":[{"type":"paragraph","attrs":{"id":"9b19aa03-a04d-404c-879e-c02fdcb4a0c5","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"问题"},{"type":"hardBreak","attrs":{"id":"9ac81b2a-1c5f-44ea-a8af-69df9ee0368c"}},{"type":"text","text":"科目余额、月度发生额里藏着异常跳变（如某月费用暴增）。靠肉眼看全量数据不现实。用 Z-score 和 IQR 两种统计法自动标出离群点。"}]},{"type":"paragraph","attrs":{"id":"3766b423-68bd-4f1d-8f5c-5ca8ea5f7286","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"示例代码"}]},{"type":"paragraph","attrs":{"id":"718ee323-1479-4fc7-81e5-0e55f4868fe5","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","marks":[{"type":"textStyle","attrs":{"color":"","background":""}}],"text":"plaintext"}]},{"type":"codeBlock","attrs":{"id":"f62389c0-095e-44a0-b4a8-03cbda867507","language":"javascript","theme":"atom-one-dark","runtimes":0,"isHoverDragHandle":false,"key":"","languageByAi":"javascript"},"content":[{"type":"text","text":"import pandas as pd\nimport numpy as np\n\ndef zscore_outliers(s, threshold=3):\n z = (s - s.mean()) / s.std(ddof=0)\n return s[abs(z) > threshold]\n\ndef iqr_outliers(s, k=1.5):\n q1, q3 = s.quantile(0.25), s.quantile(0.75)\n iqr = q3 - q1\n lo, hi = q1 - k * iqr, q3 + k * iqr\n return s[(s < lo) | (s > hi)]\n\ndf = pd.DataFrame({\"month\": range(1, 13),\n \"expense\": [10,11,9,12,10,11,10,9,45,11,10,12]})\nprint(\"Z-score 离群:\", zscore_outliers(df[\"expense\"]).tolist())\nprint(\"IQR 离群:\", iqr_outliers(df[\"expense\"]).tolist())\n"}]},{"type":"paragraph","attrs":{"id":"9492ddc9-cefc-491e-8661-18454801fd9b","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"关键点"}]},{"type":"bulletList","attrs":{"id":"41203e52-9ba1-4f7f-8d20-56420a9fd2e1","isHoverDragHandle":false},"content":[{"type":"listItem","attrs":{"id":"8407d33d-c763-420a-91fe-bcd66e55b848"},"content":[{"type":"paragraph","attrs":{"id":"489b6dac-fd1f-4b8f-8a49-d99218ea834a","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"Z-score 适合近似正态分布数据，|z|>3 约为千分之三概率，标极端值；对偏态数据会漏报。"}]}]},{"type":"listItem","attrs":{"id":"4d7d2f35-932a-4839-b4df-5044a51e6265"},"content":[{"type":"paragraph","attrs":{"id":"73809c39-c311-4a97-80d8-c3419fb8b72d","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"IQR（四分位距）对偏态、含极端值更稳健，实务推荐默认 k=1.5，可疑的用 k=3。"}]}]},{"type":"listItem","attrs":{"id":"b1cf3be7-15dd-4e89-8259-b19790aee2ce"},"content":[{"type":"paragraph","attrs":{"id":"4636f94a-d4d0-43dc-ab40-b1e2f4dd9073","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"离群点≠错报，只是“值得查”的红旗；标出后人工看凭证，别直接判舞弊。"}]}]}]},{"type":"paragraph","attrs":{"id":"9ef5842a-e158-40d4-8fde-aa6eba6db681","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"小结"},{"type":"hardBreak","attrs":{"id":"fe02d1be-1917-44fa-b13b-f8d20c17a159"}},{"type":"text","text":"异常检测 = 把“凭感觉找”变成“按阈值标”。Z-score 看正态、IQR 看偏态，双法互补。"}]},{"type":"horizontalRule","attrs":{"id":"043b540b-ca59-49ef-b375-7c8b01a74308","isHoverDragHandle":false}},{"type":"paragraph","attrs":{"id":"b36d9fe3-4441-42d2-82ce-be5f3df21fad","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"你更常用 Z-score 还是 IQR 筛异常？遇到过哪种法漏报？评论区聊。"}]},{"type":"paragraph","attrs":{"id":"fe836ff2-023d-40e8-86fc-2bd2b2801c46","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"如果有用，点赞收藏关注，留下审计难题。下期预告：毛利率同业对标分析（行业基准导入与偏离预警）。"}]},{"type":"paragraph","attrs":{"id":"4c6599e2-b4d9-487e-8316-cf5ea2079f00","textAlign":"inherit","indent":0,"color":null,"background":null,"isHoverDragHandle":false},"content":[{"type":"text","text":"会计师事务所的一名注册会计师"}]}]}