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Hand-out%204 - and sums of squares in statistics (see also...

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The summation operator and its properties We have seen in Section 1.3 that the calculation of the sample mean is based on a sum (divided by n ) – the sum in question is the sum of n individual observations, whereas we have just learned in Section 1.4 that the calculation of the sample variance is based on a sum of squares (divided by n - 1) – the sum of squares in question is the sum of squared differences between each of the observations and the sample mean. Thus, it appears important to know how to work with sums
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Unformatted text preview: and sums of squares in statistics (see also Chapters 5 and 6)! The use of the summation operator goes beyond sums and sums of squares; see the sums of cross-products in Sections 5.6 and 5.7. Knowing the properties of the summation operator may help you save some precious time, especially if you have to apply a linear transformation to your data (see property E4 on page 26 in the lecture notes) It may also lead you to make some discoveries (see Section 1.6)...
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This note was uploaded on 04/18/2008 for the course AEMA 310 taught by Professor Dutieulle during the Spring '08 term at McGill.

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