Activity Number:
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63
- Power and Sample Size: Methods and Applications
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Type:
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Contributed
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Date/Time:
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Monday, August 3, 2020 : 10:00 AM to 2:00 PM
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Sponsor:
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Biopharmaceutical Section
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Abstract #313862
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Title:
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Power Formulas for Mixed Effects Models with Random Slope and Intercept Comparing Rate of Decline Across Groups
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Author(s):
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Yu Zhao* and Sarah J Banks and Mark W Bondi and Steven D Edland
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Companies:
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UC-San Diego and UC San Diego and UC San Diego and UC San Diego
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Keywords:
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Mixed Effects Model;
Sample Size
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Abstract:
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We have previously derived power calculation formulas for cohort studies and clinical trials using the longitudinal mixed effects model with random slopes and intercepts to compare rate of change across groups [Ard & Edland, 2011; doi: 10.3233/JAD-2011-0062]. We here generalize these power formulas to accommodate 1) missing data due to study subject attrition common to longitudinal studies, 2) unequal sample size across groups, and 3) unequal variance parameters across groups. Accurate power formulas accommodating study subject dropout and these other factors ensure efficient and appropriately powered investigations. Moreover, these more general power formulas are a useful resource for understanding the relative influence of these multiple factors on the efficiency of cohort studies and clinical trials.
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Authors who are presenting talks have a * after their name.