Optical elements for semiconductor light emitting devices include a body that is configured to attach to a semiconductor light emitting device. The method generates multiple imputations comprising a set of complete data sets each containing one of a plurality of imputed realizations for the missing data values in the original data set, so that the variability in the magnitudes of these missing data values can be captured for subsequent statistical analysis. The conduit is configured to receive and provide fluid communication of a fluid stream having a charged nanometer particle mixture.