ch24confidenceintervalforsigma

ch24confidenceintervalforsigma - Chapter 24: CI for σ....

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Unformatted text preview: Chapter 24: CI for σ. Just for Interest! Not for exams Not Not covered in example classes Not Chapter 24: Chapter Confidence Interval for σ Consider the one-population case, N(μ,σ²). ²). Ifμand σare unknown, we take a sample, If and are x1 , x2 ,.........., xn , to make inferences on them. We have done the following: We It can be seen that there is one problem left: to calculate the It confidence interval for σ. We shall not go into the theoretical aspects as it is beyond the scope of this book. We simply refer to Table 8 instead. We Example 1: Example Consider the 10 data of Example 1, Chapter 22(B): 14.2, 16.7, 13.6, 12.8, 12.6, 14.5, 15.1, 15.4, 13.2, 14.9 14.2, Construct a 90% confidence interval for σ. Construct Solution: From the data, we have s = 1.285, d.f. = 9 From Table 8, we have C L = 0.729 C R = 1.645 From ∴ CI (σ ) 0.90 = (C L ⋅ s, C R ⋅ s ) = (0.729 × 1.285,1.645 × 1.285) = (0.937,2.114) ...
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