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发帖数: 147 | 1 【 以下文字转载自 Statistics 讨论区 】
发信人: CAEFIMOTO (CXO), 信区: Statistics
标 题: How to calculate overall standard deviation for these two cases?
发信站: BBS 未名空间站 (Wed Jan 5 09:15:49 2011, 美东)
Case 1:
There is only 1 sample with 3 tests.
Test 1, test points=n1, mean=mu1, standard deviation=s1;
Test 2: n2, mu2, s2;
Test 3: n3, mu3, s3.
How to calculate the overall standard deviation for this case?
Case 2:
There are 2 samples, each has 3 tests like Case 1. How to calculate overall
standard deviation for this case? (Sample 1 and 2 supposed to be the same
with production variations).
Thanks much in advance! |
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