نتایج جستجو برای: missing at random

تعداد نتایج: 3947812  

2015
Farzad Noorian

GECCO 2015 industrial challenge [1] aimed to compare procedures for recovering missing information in a heating system. In this competition, four timeseries (Figure 1) were provided, measuring water temperature or heating power at minutely intervals. To simulate missing data, parts of the time-series were dropped, with size and frequency of the gaps sampled from an exponential distribution func...

2010
Dan Jackson Ian R White Morven Leese

When a randomized controlled trial has missing outcome data, any analysis is based on untestable assumptions, e.g. that the data are missing at random, or less commonly on other assumptions about the missing data mechanism. Given such assumptions, there is an extensive literature on suitable methods of analysis. However, little is known about what assumptions are appropriate. We use two sources...

Journal: :Journal of biopharmaceutical statistics 2009
Ohidul Siddiqui H M James Hung Robert O'Neill

In recent years, the use of the last observation carried forward (LOCF) approach in imputing missing data in clinical trials has been greatly criticized, and several likelihood-based modeling approaches are proposed to analyze such incomplete data. One of the proposed likelihood-based methods is the Mixed-Effect Model Repeated Measure (MMRM) model. To compare the performance of LOCF and MMRM ap...

2015
Stanley Xu Emily B. Schroeder Susan Shetterly Glenn K. Goodrich Patrick J. O’Connor John F. Steiner Julie A. Schmittdiel Jay Desai Ram D Pathak Romain Neugebauer Melissa G. Butler Lester Kirchner Marsha A. Raebel David G. Yu

In studies that use electronic health record data, imputation of important data elements such as Glycated hemoglobin (A1c) has become common. However, few studies have systematically examined the validity of various imputation strategies for missing A1c values. We derived a complete dataset using an incident diabetes population that has no missing values in A1c, fasting and random plasma glucos...

1997
Mortaza Jamshidian Peter M. Bentler

We consider maximum likelihood (ML) estimation of mean and covariance structure models when data are missing. Expectation maximization (EM), generalized expectation maximization (GEM), Fletcher-Powell, and Fisherscoring algorithms are described for parameter estimation. It is shown how the machinery within a software that handles the complete data problem can be utilized to implement each algor...

Journal: :Pacific Symposium on Biocomputing. Pacific Symposium on Biocomputing 2017
Brett K. Beaulieu-Jones Jason H. Moore et al.

Electronic health records (EHRs) have become a vital source of patient outcome data but the widespread prevalence of missing data presents a major challenge. Different causes of missing data in the EHR data may introduce unintentional bias. Here, we compare the effectiveness of popular multiple imputation strategies with a deeply learned autoencoder using the Pooled Resource Open-Access ALS Cli...

2011
YVES F. ATCHADÉ

We consider the estimation of high-dimensional network structures from partially observed Markov random field data using a `-penalized pseudo-likelihood approach. We fit a misspecified model obtained by ignoring the missing data problem. We derive an estimation error bound that highlights the effect of the misspecification. We report some simulation results that illustrate the theoretical findi...

Journal: :Statistics in medicine 2007
X M Tu C Feng J Kowalski W Tang H Wang C Wan Y Ma

Correlation analysis is widely used in biomedical and psychosocial research for assessing rater reliability, precision of diagnosis and accuracy of proxy outcomes. The popularity of longitudinal study designs has propelled the proliferation in recent years of new methods for longitudinal and other multi-level clustered data designs, such as the mixed-effect models and generalized estimating equ...

Journal: :Statistics in medicine 2003
Andreas Ziegler Christian Kastner Jenny Chang-Claude

Generalized estimating equations have been well established to draw inference for the marginal mean from follow-up data. Many studies suffer from missing data that may result in biased parameter estimates if the data are not missing completely at random. Robins and co-workers proposed using weighted estimating equations (WEE) in estimating the mean structure if drop-out occurs missing at random...

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