09_25ans - STAT 420 2. Examples for 09/25/2007 Fall 2007...

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STAT 420 Examples for 09/25/2007 Fall 2007 2. The upper management at Initech wants to examine the relationship between the number of years on the job ( x ) and the number of TPS reports produced ( y ) for the middle-management employees. The data are as follows: x y 1 7 2 4 3 13 3 10 4 10 5 16 Compute the correlation coefficient between x and y . x y x x - y y - ( ) 2 x x - ( ) ( ) y y x x - - ( ) 2 y y - 1 7 – 2 – 3 4 6 9 2 4 – 1 – 6 1 6 36 3 13 0 3 0 0 9 3 10 0 0 0 0 0 4 10 1 0 1 0 0 5 16 2 6 4 12 36 Total: 18 60 0 0 10 24 90 6 18 = = n x x = 3. 6 60 = = n y y = 10. r = ( ) ( ) ( ) ( ) 90 10 24 2 2 = & - - - - y y x x y y x x = 0.8 .
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3. The following data are indexed prices of gold and copper over a 10-year period. Assume that the indexed values constitute a random sample from a bivariate normal distribution. x y x x - y y - ( ) 2 x x - ( ) ( ) y y x x - - ( ) 2 y y - 76 80 16 12 256 192 144 62 68 2 0 4 0 0 70 73 10 5 100 50 25 59 60 1 8 1 8 64 53 64 7 4
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09_25ans - STAT 420 2. Examples for 09/25/2007 Fall 2007...

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