نتایج جستجو برای: missing at random

تعداد نتایج: 3947812  

Background Policy makers need models to be able to detect groups at high risk of HIV infection. Incomplete records and dirty data are frequently seen in national data sets. Presence of missing data challenges the practice of model development. Several studies suggested that performance of imputation methods is acceptable when missing rate is moderate. One of the issues which was of less concern...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد مرودشت - دانشکده علوم تربیتی و روانشناسی 1392

the purpose of this study was to investigate the relationship between family functioning and marital adjustment humor couples are due to the nature and objectives of the research and application of methods for its implementation correlation was used. the study population consisted of all the couples in the city who uses random cluster sampling of 200 students were selected as sample. data from ...

2014
Wangyan Li Guoliang Wei Licheng Wang Zidong Wang

This paper is devoted to the problems of gain-scheduled control for a class of discretetime stochastic systems with infinite-distributed delays and missing measurements by utilizing probability-dependent Lyapunov functional. The missing-measurement phenomenon is assumed to occur in a random way, and the missing probability is time varying with securable upper and lower bounds that can be measur...

Journal: :Behavior research methods 2012
Damazo T Kadengye Wilfried Cools Eva Ceulemans Wim Van den Noortgate

Missing data, such as item responses in multilevel data, are ubiquitous in educational research settings. Researchers in the item response theory (IRT) context have shown that ignoring such missing data can create problems in the estimation of the IRT model parameters. Consequently, several imputation methods for dealing with missing item data have been proposed and shown to be effective when a...

Journal: :Statistics in medicine 2008
Roch Giorgi Aurélien Belot Jean Gaudart Guy Launoy

Relative survival assesses the effects of prognostic factors on disease-specific mortality when the cause of death is uncertain or unavailable. It provides an estimate of patients' survival, allowing for the effects of other independent causes of death. Regression-based relative survival models are commonly used in population-based studies to model the effects of some prognostic factors and to ...

Journal: :Clinical trials 2014
Karla Díaz-Ordaz Michael G Kenward Abie Cohen Claire L Coleman Sandra Eldridge

BACKGROUND Missing data are a potential source of bias, and their handling in the statistical analysis can have an important impact on both the likelihood and degree of such bias. Inadequate handling of the missing data may also result in invalid variance estimation. The handling of missing values is more complex in cluster randomised trials, but there are no reviews of practice in this field. ...

2009
Nicolas Städler Peter Bühlmann

We propose an `1-regularized likelihood method for estimating the inverse covariance matrix in the high-dimensional multivariate normal model in presence of missing data. Our method is based on the assumption that the data are missing at random (MAR) which entails also the completely missing at random case. The implementation of the method is non-trivial as the observed negative log-likelihood ...

Journal: :Statistica Sinica 2014
Hongtu Zhu Joseph G Ibrahim Niansheng Tang

Methods for handling missing data depend strongly on the mechanism that generated the missing values, such as missing completely at random (MCAR) or missing at random (MAR), as well as other distributional and modeling assumptions at various stages. It is well known that the resulting estimates and tests may be sensitive to these assumptions as well as to outlying observations. In this paper, w...

2013
Felix Thoemmes Norman Rose

The treatment of missing data in the social sciences has changed tremendously during the last decade. Modern missing data techniques such as multiple imputation and full-information maximum likelihood are used much more frequently. These methods assume that data are missing at random. One very common approach to increase the likelihood that missing at random is achieved, consists of including m...

Journal: :Multivariate behavioral research 2014
Felix Thoemmes Norman Rose

The treatment of missing data in the social sciences has changed tremendously during the last decade. Modern missing data techniques such as multiple imputation and full-information maximum likelihood are used much more frequently. These methods assume that data are missing at random. One very common approach to increase the likelihood that missing at random is achieved consists of including ma...

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