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In statistics the assumed mean is a method for calculating the arithmetic mean and standard deviation of a data set. It simplifies calculating accurate values by hand. Its interest today is chiefly historical but it can be used to quickly estimate these statistics. There are other rapid calculation methods which are more suited for computers which also ensure more accurate results than the obvious methods. ==Example== First: The mean of the following numbers is sought: : 219, 223, 226, 228, 231, 234, 235, 236, 240, 241, 244, 247, 249, 255, 262 Suppose we start with a plausible initial guess that the mean is about 240. Then the deviations from this "assumed" mean are the following: : −21, −17, −14, −12, −9, −6, −5, −4, 0, 1, 4, 7, 9, 15, 22 In adding these up, one finds that: : 22 and −21 almost cancel, leaving +1, : 15 and −17 almost cancel, leaving −2, : 9 and −9 cancel, : 7 + 4 cancels −6 − 5, and so on. We are left with a sum of −30. The ''average'' of these 15 deviations from the assumed mean is therefore −30/15 = −2. Therefore that is what we need to add to the assumed mean to get the correct mean: : correct mean = 240 − 2 = 238. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Assumed mean」の詳細全文を読む スポンサード リンク
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