Statistics: Informed Decisions Using Data (4th Edition)

Published by Pearson
ISBN 10: 0321757270
ISBN 13: 978-0-32175-727-2

Chapter 10 - Section 10.6 - Assess Your Understanding - Applying the Concepts - Page 521: 16

Answer

$β=0.8790$ Power of the test: $1-β=0.1210$ As the level of significance decreases, the power of the test decreases too. Remember that $α=P(Type~I~error)$ and that as α decreases, $β=P(Type~II~error)$ increases. But, the power of the test is equal to $1 - β$. So, if $β$ increases, the power of the test decreases.

Work Step by Step

$z_α=z_{0.01}$ If the area of the standard normal curve to the right of $z_{0.01}$ is 0.01, then the area of the standard normal curve to the left of $z_{0.01}$ is $1−0.01=0.99$ According to Table V, the z-score which gives the closest value to 0.99 is 2.33. $p ̂=p_0+z_α.\sqrt {\frac{p_0(1-p_0)}{n}}$ $p ̂=0.40+2.33\sqrt {\frac{0.40(1-0.40)}{200}}=0.481$ $β=P(Type~II~error)=P(p ̂\lt0.481~given~that~p=0.44)$ $β=P(z\lt\frac{0.481-0.44}{\sqrt {\frac{0.44(1-0.44)}{200}}})=P(z\lt1.17)=0.8790$ Power of the test: $1-β=0.1210$
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