Answered: You are designing a two-arm…

Big Ideas Math A Bridge To Success Algebra 1: Student Edition 2015

1st Edition

ISBN:9781680331141

Author:HOUGHTON MIFFLIN HARCOURT

Publisher:HOUGHTON MIFFLIN HARCOURT

Chapter4: Writing Linear Equations

Section: Chapter Questions

Problem 14CR

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Question

You are designing a two-arm parallel-groups trial of a new blood pressure-lowering medication compared to an already approved blood pressure-lowering medication (1:1 allocation). The pharmaceutical sponsor is interested in detecting a between-group difference of 6 mmHg in diastolic blood pressure (DBP) at 6 months.

(a) The within-person variance in DBP is 36.3 mmHg², the between-person variance in DBP is 58.4 mmHg², and the total variance in DBP is 94.7 mmHg². Which estimate of variability do you need to compute sample size for this trial?

(b) How many participants will need to be enrolled? Set power at 90% and (two-sided) type I error at 5%. Be sure to show all steps of your calculations. (If you solve this problem using a formula, be sure to write the formula and identify all of the inputs as well as the result of the calculation. If you solve this problem with an external sample size calculator, be sure to identify the calculator (e.g., an online link), what your inputs were, what the output is, and what that output represents.)

(c) However, you advise the sponsor that in your experience 12% of participants will be lost to follow-up over 6 months. For what sample size should the sponsor budget? Justify your answer.

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