Answered: In a 5-year follow-up of bilateral…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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In a 5-year follow-up of bilateral stimulation of the subthalamic nucleus among 49 patients with advanced Parkinson's disease, investigators assessed changes in symptoms as measured by the Unified Parkinson's Disease Rating Scale (range= 0 to 108, with higher values denoting more symptoms). Assume this measure follows a normal distribution. The mean score at baseline was 55.7. The standard deviation of change from baseline to 5 years was 15.3.

What minimum sample size would be needed to detect a mean change of 5 units with 80% power if a two-sided test is used with alpha=0.05?

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The given data is, In a 5-year follow-up of bilateral stimulation of the subthalamic nucleus among 49 patients with advanced Parkinson's disease, investigators assessed changes in symptoms as measured by the Unified Parkinson's Disease Rating Scale.

Assume this measure follows a normal distribution. The mean score at baseline was 55.7. The standard deviation of change from baseline to 5 years was 15.3.

The mean change of 5 units means

$µ_{1} - µ_{2} = 5 A s, α = 0.05 t h e n Z_{α / 2} = 1.96 . . U \sin g s t a t i s t i c a l T a b l e A s p o w e r = 80 % = 0.80 t h e n Z_{β} = 0.84 . . . U \sin g s t a t i s t i c a l T a b l e$

σ=15.3

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