Imbalance between groups

Group 2 Coke imbalance. This grouping considers malfunctions leading to a difference between the rate at which coke accumulates on the catalyst and the rate at which it is burned off. A coke imbalance is associated with a reduction of oxygen, which can be caused by a loss of combustion air or through an increase in the conradson carbon in the gas oil feed to the unit. 

G10. Girardin, E., Roux-Lombard, P Grau, G. E., Suter, P., and Gallati, H., and Dayer J. M. The J5 Study Group. Imbalance between tumour necrosis factor-alpha and soluble TNF receptor concentrations in severe meningococcaemia. Immunology 76,20-23 (1992). 

It is concluded that the selectivities of electrophilic additions are not directly related to the reactivities but to the transition-state positions. Extensive comparison with similar data on the bromination and hydration of other ethylenic compounds bearing a conjugated group shows that this unexpected reactivity-selectivity behaviour can arise from an imbalance between polar and resonance effects (Ruasse, 1985). Increasing resonance in the ground state would make the transition state earlier and attenuate the kinetic selectivity more strongly than it enhances the reactivity. Hydration and halogenation probably respond differently to this imbalance. 

When there is some imbalance between the treatment groups in a baseline covariate that is solely due to chance then adjusted treatment effects may account for this observed imbalance when unadjusted analyses may not. If the imbalance is such that the experimental group has a better prognosis than the control group, then adjusting for the imbalance is particularly important. Sensitivity analyses should be provided to demonstrate that any observed positive treatment effect is not solely explained by imbalances at baseline in any of the covariates. ... 

While the group was in good shape from the very beginning, I had to accommodate to the imbalance between inorganic and organic chemistry in the Zurich department. In contrast to Munchen, its resources in terms of lab space and assistantships were distributed in a ratio of 1 3 in favor of the organic section. The reason was that when Alfred Werner (Fig. 2.18) retired, he was succeeded by his former student Paul Karrer (Nobel laureate 1937), who became... 

Table 9.5 Triad decision matrix showing the results from all tests on a quantitative effect scale. The tests are grouped per Triad leg, and the geometric mean of (1—effect) is calculated. The values in bold type are gross effect levels. Back transformation gives the integrated effect value for all tests per Triad leg. In the lower part of the matrix, all integrated results are summarized and the final risk is calculated, including a deviation factor for demonstrating imbalance between results from different Triad legs.

Obviously, the degree of imbalance observed in a randomized clinical trial will vary randomly. On average the difference at baseline between groups will be zero. This does not imply, however, that the average value of A 2 will be 1. A2 is, in fact related to familiar quantities from the analysis of variance the numerator of the second term is simply the between sum of squares and the denominator is the within sum of squares for a one-way layout with n observations in each group. Since the sum of squares between has one degree of freedom, it is equal to the mean square between, MSB, whereas the within sums of squares has 2(n — 1) degrees of freedom and hence is 2(n — 1) MSW, where MSW is the mean square within. Hence,... 

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