ec6a - The University of Hong Kong Department of Statistics...

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1 The University of Hong Kong Department of Statistics and Actuarial Science STAT0302 Business Statistics Semester 2 2009/2010 Example Class 6 Suggested Solution 1. (a) (i) 15 1.0 28 2.7 13 1.3 20 1.9 4 0.9 10 1.7 166.1 ii xy   2 2 2 2 2 2 2 15 28 13 20 4 10 1694 i x   1 15 28 13 20 4 10 15 6 x     1 1.0 2.7 1.3 1.9 0.9 1.7 9.5 6 6 y 22 2 166.1 6 15 9.5 6 0.068607 1694 6 15 xy xx i S x y nxy b S x nx    9.5 6 0.068607 15 0.5542 a y bx Hence, 0.5542 0.0686 yx  (ii) With calculator fx-50FH: Step 1: Change to REG mode. Press MODE Lin  . Remarks: appears on the screen Step 2: Clear the memory in the calculator. Press SHIFT CLR Stat EXE . Step 3: Enter the data in sequence. Press 15 , 1 28 , 2.7 13 , 1.3 20 , 1.9 4 , 0.9 10 , 1.7 MM       Step 4: Display the number of data. Press S SUM n . This gives 6 n Step 5: Find a . Press S Var Var a . This gives 0.5542 a Step 6: Find b . Press S Var Var b . This gives 0.0686 b
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STAT0302 Business Statistics Example Class 6 2 (b) The regression line is 0.5542 0.0686 yx  0 0.5 1 1.5 2 2.5 3 0 5 10 15 20 25 30 (c) 0.5542 0.0686 20 1.9262 y (d) 0.5542 0.0686 0 0.5542 y   (e) The prediction which is more reliable is (c), because (c) is interpolation whereas (d) is extrapolation. Interpolation means the given x - value is within the available data range while extrapolation means it is outside the available data range. For example, in (c) the given x - value is 20 which falls in the data range given by 4 to 28. Outside the available data range, the regression line may not be valid.
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This note was uploaded on 05/02/2010 for the course STAT STAT0302 taught by Professor Prof.chiu during the Spring '09 term at HKU.

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ec6a - The University of Hong Kong Department of Statistics...

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