Effect of Rancher’s Management Philosophy, Grazing Practices, and Personal Characteristics on Sustainability Indices for North Central Texas Rangeland Page: 63
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weighted mean of k nearest neighbors, where 1 row (case) is represented as one gene (Kim et al.,
While much of the literature implies the use of 'seqKNN' with the use of missing data
concerning gene expression (Hastie et al., 1999; Kim et al., 2004; Kim et al., 2009), the package
'seqKNN' uses Euclidean distance to impute missing data and is applicable for many situations.
This method is quite simple in principle but is effective and often preferred over other methods
Nearest neighbors are records that have similar completed data patterns; the average of the k-
nearest neighbor's completed data are used to impute the value for a variable that is missing its
value (where k can be set by the analyst or R user) (Kim and Yi, 2008; Starkweather, 2010Ob).
Hastie, et al. (1999) have shown choosing k ranging from 5 to 10 is adequate.
The advantage of the knn approach is that it missing data only depends on the observed
data. This package assumes data are missing at random. This then allows the knn approach to
take advantage of multivariate relationships in the completed data. The disadvantage of this
approach is it does not include a component to model random variation; consequently
uncertainty in the imputed value is underestimated (Starkweather 2011 a).
Imputation of missing values was conducted using package 'SeqKnn' in R version 2.13.0
(Kim and Yi, 2009). Imputed values were used throughout all analyses during inferential
statistical procedures. For the purposes of these analyses, 5 was chosen as k.
Data imputed with the R package 'SeqKnn' was not necessarily a whole number. In order to
have these values fit into the ordered and nominal data categories insuring consistency with other
data, these values were rounded to the nearest whole number. This task was accomplished using
the 'round' function which is available with the 'base' package of R version 2.13.0. (R-2.13.0,
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Becker, Wayne. Effect of Rancher’s Management Philosophy, Grazing Practices, and Personal Characteristics on Sustainability Indices for North Central Texas Rangeland, dissertation, December 2011; Denton, Texas. (digital.library.unt.edu/ark:/67531/metadc103289/m1/74/: accessed March 25, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .