Subgroup testing

Note however that the hazard ratio in both high and low baseline LDL cholesterol subgroups is below 1.00 indicating a benefit of pravastatin (a quantitative interaction), although this benefit is marginal in those patients presenting with LDL cholesterol 4.0mmol/l. 

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Table 8.3 Impact of multiple subgroup testing on the overall probability of at least one type-I error...

It is not easy to obtain measures on hundreds of patients. This is particularly an issue when investigating more specific subgroups, such as those we discussed for the mood disorders. Conceivably, the taxonicity of 296.40 with seasonal pattern can be tested separately from 296.40 with rapid cycling, but of course, these analyses would require access to extremely large samples. 

As an illustrative example of stress-testing W1 and W2 theory, we shall consider the benzene molecule. The most accurate calculation we were able to carry out is at the W2h level the rate-determining step was the direct CCSD/cc-pV5Z calculation (30 electrons correlated, 876 basis functions, carried out in the D h subgroup of DGh) which took nearly two weeks on an Alpha EV67/667 MHz CPU. Relevant results are collected in Table 2.5. 

The 222 enthalpies of formation included in the G3/99 test set contain a wide variety of molecules with many different kinds of bonds. They are conveniently classified into subgroups of molecules. They include 47 molecules containing non-hydrogen atoms, 38 hydrocarbons, 91 substituted hydrocarbons, 15 inorganic hydrides, and 31 open-shell radicals. Together, they provide a comprehensive assessment of new theoretical models in a wide variety of bonding environments. 

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