کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
415121 681179 2010 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
DD-optimality of unequal versus equal cluster sizes for mixed effects linear regression analysis of randomized trials with clusters in one treatment arm
موضوعات مرتبط
مهندسی و علوم پایه مهندسی کامپیوتر نظریه محاسباتی و ریاضیات
پیش نمایش صفحه اول مقاله
DD-optimality of unequal versus equal cluster sizes for mixed effects linear regression analysis of randomized trials with clusters in one treatment arm
چکیده انگلیسی

The efficiency loss due to varying cluster sizes in trials where treatments induce clustering of observations in one of the two treatment arms is examined. Such designs may arise when comparing group therapy to a condition with only medication or a condition not involving any kind of treatment. For maximum likelihood estimation in a mixed effects linear regression, asymptotic relative efficiencies (RE  ) of unequal versus equal cluster sizes in terms of the DD-criterion and DsDs-criteria are derived. A Monte Carlo simulation for small sample sizes shows these asymptotic RE  s to be very accurate for the DsDs-criterion of the fixed effects and rather accurate for the DD-criterion. Taylor approximations of the asymptotic REs turn out to be accurate and can be used to predict the efficiency loss when planning a trial. The RE usually will be more than 0.94 and, when planning sample sizes, multiplying both the number of clusters in one arm and the number of persons in the other arm by 1/RE is the most cost-efficient way of regaining the efficiency loss.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Computational Statistics & Data Analysis - Volume 54, Issue 8, 1 August 2010, Pages 1906–1920
نویسندگان
, ,