We carried out a profile preprocessing step on the samples, which included filtering out data with more than 5% missing values, combining probes of the same gene, and then filling missing values using the K-neighbors algorithm.
Finally, the matching and missing values are combined globally using the generalized formula.
Before the upload, R scripts (R version 3.0.2) process the data to address missing values, to combine separate files into one where necessary, to reformat the data and to generate SQL scripts for the data upload.
Because the use of missing indicator categories can possibly introduce bias, we ran the same models using the multiple imputation procedure in SAS (PROC MI and MIANALYZE) to impute missing values and combine results from ten imputations as has been described elsewhere (Graham 2009).
There were few inconsistencies between independent DArT analyses, which were entered as missing values in the combined DArT marker set.
These data also had a higher number of missing values owing to the combined effects of item-non-response and drop out in subsequent waves.
For all questions, "Not applicable" was included as a response category, and combined with missing values in the data analyses.
In this paper, we introduce a generalized formula to combine matching and missing values.
This subsection explains a generalized algorithm that combines matching and missing values globally.
In this paper, authors introduce a generalized formula to combine matching and missing values.
