Qualitative versus quantitative

Disagreement exists about how to determine effectiveness of cholinesterase inhibitors. Selection of qualitative versus quantitative assessment may bias a clinician s impression of response. Subtle changes are often detected only by psychometric testing rather than with routine questioning. No standard has been suggested to define the effectiveness of these medications therefore great variation exists between clinicians, and the duration of treatment ranges from months to years. 

QUALITATIVE VERSUS QUANTITATIVE SUSCEPTIBILITY TESTING OF MICROORGANISMS... 

Qualitative versus Quantitative Techniques for Safety Risk Assessments... 

We started this review with a brief discussion of some apparent dilemmas that we face in chemistry qualitative versus quantitative approaches, observables versus non-observables, structural criteria versus properties as criteria for characterization of aromaticity, chemical graph theory versus quantum chemistry, Clar 6/j rule versus Huckel An+ 2 rule, and hydrocarbons versus heteroatomic systems. As we have seen, most of the mentioned dilemmas are man-made and reflect inbred biases of different circles of chemists. It is not uncommon to come across critics with strong opinions and weak arguments, and it would be a waste of time to try to point out to them the other side of the coin . Max Planck apparently experienced difficult times before his quantum constant was accepted, as is reflected in the following quotations ... 

The fractionation patterns exhibited % successive members of a progression of polyads (along 02, CC stretch, or along v4, trans-bend) provide a surveyor s map of IVR. One can look at the 1VR trends and see whether the multiresonance model expressed in the H nres (1 polyads provides a qualitative or quantitative representation of the fractionation patterns. The dynamics of even a four-atom molecule is so complicated that, unless one knows what to look for, one can neither identify nor explain trends in the dynamics versus V2 or u4 or Evib- Moreover, by defining the pattern of the IVR and how this pattern should scale with V2, v4, or EVib, the H res / polyad model may make it possible to detect a disruption of the pattern. Such disruptions could be due to a change in the resonance structure of the exact H near some chemically interesting topographic feature of the V(Q), such as an isomerization saddle point. 

After solvent development, the detection procedures can be either qualitative or quantitative. Qualitative procedures require that a drug product be identified on the chromtographic plate as having the identical Rf and at about equal magnitude to a reference sample. Semiquantitative estimations can be a visual comparison of the size and intensity of the spots versus various standard concentrations. Quantitative procedures require either densitometry or the extraction of the components of interest from the sorbent followed by spectrophotometric measurement. 

Polyethylenes produced commercially via high pressure, free radical processes have densities around 0.92 g/cc and are referred to simply as "low density" polyethylenes. It has been well established from infrared measurements that these low density polyethylenes possess appreciable quantities of ethyl and butyl branches (1-3) but it was not until C-13 NMR became available that an absolute identification, both qualitatively and quantitatively, of the short branches became possible (4-8). Long chain branching is also present in high pressure process low density polyethylenes and carbon-13 NMR was useful here also in establishing the identity and relative amounts of long versus short chain branches (9-11). 

It is well established that AChE exists in nerves and muscles in a range of globular and asymmetric molecular forms. A wide variety of sedimentation profiles have been established for AChE moleeular forms in different mammalian muscles (Massoulie and Bon, 1982). The variations seen in the ratios of these moleeular forms between different muscles are wide and eomplex. Qualitative and quantitative variations exist among different species, as well as young versus adult (Barnard et al, 1984). In the rat extensor digitorum longus (EDL, a fast twitch muscle), the... 

Some hits also revealed sufficient selectivity of type 1 inhibition versus the type 2 isoform, which is advantageous for the side-effect profile of these compounds. Comparison of the model for llp-HSDl inhibitors with the X-ray crystal structure (which was published shortly after model generation and VS) showed good correlation of the chemical features responsible for ligand binding. In another study, a combination of common feature-based qualitative and quantitative models was used as 3D pharmacophore search query to successfully detect novel endothelin-A antagonistic lead structures. 

Qualitative Versus Quasi-Quantitative LBA Assay Formats... 

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