Statistically, the study will attempt to evaluate a null hypothesis of equivalent results with respect to these parameters between either the three types of fortifications in "Study Group 1" or the two types of overall nutrition in "Study Group 2", as compared with an alternative of some inequality between the groups, i.e. letting μ be the mean number of days of TPN any of the study arms, then for "Study Group 1 the hypotheses may be written as: