Because the more valid subtype analysis in the current study may have resulted from either a larger sample or a better subtyping method, we compared the two approaches by applying the LMW method of Chan (2011) to the larger sample available for the present analysis. To do so, we used the same programs as in the prior study (SAS and SOLAR, though the k-medoids analysis was run using the R package). We found that the current, modified approach produced not only larger clusters of higher heritability, but also more homogeneous clusters than our previous effort (Chan et al., 2011). Because the variable selection step that resulted in heritable OD measures led to more highly heritable subtypes, a thorough examination of the phenotypic measures used in subtyping methods may be necessary to optimize the procedure.
