نتایج جستجو برای: imputation
تعداد نتایج: 16711 فیلتر نتایج به سال:
We present three di erent methods based on the conditional mean im putation when binary explanatory variables are incomplete Apart from the single imputation and multiple imputation especially the so called pi imputation is presented as a new procedure Seven procedures are com pared in a simulation experiment when missing data are con ned to one independent binary variable complete case analysi...
BACKGROUND In the past decade many Genome-wide Association Studies (GWAS) were performed that discovered new associations between single-nucleotide polymorphisms (SNPs) and various phenotypes. Imputation methods are widely used in GWAS. They facilitate the phenotype association with variants that are not directly genotyped. Imputation methods can also be used to combine and analyse data genotyp...
Genomic selection, a breeding method that promises to accelerate rates of genetic gain, requires dense, genome-wide marker data. Genotyping-by-sequencing can generate a large number of de novo markers. However, without a reference genome, these markers are unordered and typically have a large proportion of missing data. Because marker imputation algorithms were developed for species with a refe...
Missing value is an unavoidable problem when dealing with real world data sources, and various approaches for dealing with missing data have been developed. In fact, it is very important to consider the imputation ordering (ordering means which missing value should be imputed at first with the help of a specific criterion) during the imputation process, because not all attributes have the same ...
BACKGROUND Multiple imputation is a popular approach to handling missing data in medical research, yet little is known about its applicability for estimating the relative risk. Standard methods for imputing incomplete binary outcomes involve logistic regression or an assumption of multivariate normality, whereas relative risks are typically estimated using log binomial models. It is unclear whe...
Random forest (RF) missing data algorithms are an attractive approach for imputing missing data. They have the desirable properties of being able to handle mixed types of missing data, they are adaptive to interactions and nonlinearity, and they have the potential to scale to big data settings. Currently there are many different RF imputation algorithms, but relatively little guidance about the...
When some observations in the sample data are missing, the application of the regression method is considered for the estimation of population mean with and without the use of imputation. The performance properties of the estimators based on the methods of mean imputation, regression imputation and no imputation are analyzed and the superiority of one method over the other is examined.
Background and Objectives: Missing data is a big challenge in the research. According to the type of the study and of the variables, different ways have been proposed to work with these data. This study compared five popular imputation approaches in addressing missing data in the questionnaires. Methods: In this study, 500 questionnaires were used for self-medication in diabetic patients. Mi...
Imputation of moderate-density genotypes from low-density panels is of increasing interest in genomic selection, because it can markedly reduce genotyping costs. Several imputation software packages have been developed; however, these vary in imputation accuracy and imputed genotypes may be inconsistent over methods. An AdaBoost-like approach was developed to combine imputation results from sev...
Multiple imputation for missing survey data is relatively new concept. As defined by one of its leading proponents, "multiple imputation is the technique that replaces each missing or deficient value with two or more acceptable values representing a distribution of possibilities" (Rubin 1987, p.2). Multiply-imputed data reflects the uncertainty contained in the imputation process in a way not p...
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