Cross-validation definition

Many people use the term PRESS to refer to the result of leave-one-out cross-validation. This usage is especially common among the community of statisticians. For this reason, the terms PRESS and cross-validation are sometimes used interchangeably. However, there is nothing inate in the definition of PRESS that need restrict it to a particular set of predictions. As a result, many in the chemometrics community use the term PRESS more generally, applying it to predictions other than just those produced during cross-validation. 

The Problem (vahdation requirements in this case) should be clearly defined with highly specific definitions for the scope and objectives of the work to be undertaken. If part of a larger program, the protocol may include an overview of all other activities relating to the work, e.g. cross validation activities at another laboratory, but more likely a vahdation protocol will be focused on the analytical portion of the study and the procedures to be conducted in a particular laboratory. 

Let us note that this definition of y breaks the limits of the Kielson-Storer model and can cause a few contradictions in interpretation of results. If the measured cross-section oj appears to be greater than oo, then, according to (3.45), the sought y does not exist. To be exact, this assertion is valid relative to the cross-section of the rotational energy relaxation oe = (1 — y2)oot since y2 is always positive. As to oj, taking into account the domain of negative values of y, corresponding to the anticorrelated case (see Chapter 2), formula (3.45) fails to define y when oj > 2co. 

A transfer of this definition of the cross-flow term to the chemical reactor field implies that the so-called cell reactor [26], consisting of thin, porous catalyst plates mounted in a rack like a filter press, should also be of interest to describe here. The same may apply to the great number of different electrochemical filter-press cell reactors [27]. It may be noted that the cell reactor principle is, however, not valid for the so-called parallel-passage reactor [28,29]. In this case the same fluid flows on both sides of the catalyst plates without any need for communication and exchange between the fluids through the plates. The advantage of this reactor is its being dust-proof, since dust present... 

The differences of the initial structure generation procedure will influence the quality of NMR structures, because of the initial structure dependency of the calculations. The ability to cross the potential barrier (i.e., conformational space exploration efficiency) definitely depends on the molecular dynamics conditions (typically simulation time). The conditions, however, are usually not validated, because of limitations by computational resources. The computing power required is linearly dependent on the simulation time, and thus has been a strong limitation of the calculations. Furthermore, temperature and steric repulsion weighing schedules as well as the force field will influence the structural quality. 

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