Ch. 1_082410 - Lab 227 08/24/10 Chapter 1 Statistical...

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Lab 227 08/24/10 Chapter 1 Statistical notation The summation notation is the Greek letter sigma : . Order of operations: 1. Any calculation within parentheses. 2. Squaring (or raising to other exponents) 3. Multiplying or dividing. 4. Summation using the ∑ 5. Any other addition or subtraction Class example A 1. calculate ∑X, ∑X 2 , (∑X) 2 on the following scores: 4, 2, 8, 3. X X 2 4 16 2 4 8 64 3 9 ∑X = 17 ∑X 2 = 93 (∑X) 2 = 289 2. On the same scores, calculate ∑(X-1), ∑(X-1) 2 X X 2 (X-1) (X-1) 2 4 16 3 9 2 4 1 1 8 64 7 49 3 9 2 4 ∑X = 17 ∑X 2 = 93 ∑(X-1)= 13 ∑(X-1) 2 = 63 (∑X) 2 = 289 Class example B In some cases we may have more than one score for each person. Person X Y XY A 4 5 20 B 2 3 6 C 8 4 32 D 3 2 6 ∑X = 17 ∑Y = 14 ∑X Y= 64
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Class example C Calculate ∑X 2 , (∑X) 2 , ∑(X-3), ∑(X-3) 2 , and ∑(X 2 –3)on the following scores: 4, 0, 0, 8 X X 2 (X-3) (X-3) 2 (X 2 –3) 4 16 1 1 13 0 0 -3 9 -3 0 0 -3 9 -3 8 64 5 25 61 ∑X = 12 ∑X 2 = 80 ∑(X-3)= 0 ∑(X-3) 2 = 44 ∑(X 2 –3)=68 (∑X) 2 = 144 Class example D Calculate ∑X 2 , (∑X) 2 , ∑(X+3), and ∑(X+3) 2 on the following scores: 5, -1, 0, -3, 4 X X 2 X+3 (X+3) 2 5 25 8 64 -1 1 2 4 0 0 3 9 -3 9 0 0 4 16 7 49 ∑X = 5 ∑X
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Ch. 1_082410 - Lab 227 08/24/10 Chapter 1 Statistical...

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