Fisher weighting

The Fisher ratio F. of feature i for a binary classification problem is given by equation (99) C376, 4163. 

Fisher ratios have a great dynamic range variing from zero if the classes have the same mean to some large value for well separated classes. 

Instead of the Fisher ratio an easier to calculate weight was proposed by Coomans et.al. C553 (equation (100)). 

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Fisher weight Fishing lines Fishing rods Fish meal Fish oil Fish oils Fish paste... 

Table 1. Variance and Fisher Weights in the Forensic Paper Study ...

When feature selection is used to simplify, because of the large number of variables, methods must be simple. The univariate criterion of interclass variance/intraclass variance ratio (in the different variants called Fisher weights variance weights or Coomans weights is simple, but can lead to the elimination of variables with some discriminant power, either separately or, more important, in connection with other variables (Fig. 36). 

Fig. 36a-d. Some examples of single variables (a, b) or variable pairs (c, d) whose discriminant power cannot be detected by univariate Fisher weights. The transforms y + x (a) and y/x (b) have high univariate weight... 

Selection procedures ----= Fisher --------= weighted w -------= unweighted w. Selection... 

Fig. 4.20 NLM of a set of NOA samples described by Fisher-weighted sensory QDA data. Symbols are the same as those used in Fig. 4.14 (from Lin et al. 1993, with permission of...

Fisher-weighting and variance-weighting are different procedures for weighting variables according to their ability to classify samples (see Varmuza 1980). 

Permeability is another method for obtaining information about pcirticle diameters. If one packs a tube with a weight of powder exactly equal to its density, and applies a calibrated gas pressure through the tube, the pressure drop can be equated to an average particle size. The instrument based on this principle is called the "Fisher Sub-Sieve Sizer ". Only one value can be obtained but the method is fast and reproducible. The instrument itself is not expensive and the method can be applied to quality control problems of powders. Permeametry is usefiil in the particle range of 0.5 to 50 n. 

Shimadzu Xex = 486nm, A,em = 516 nm) with a chart recorder (Fisher Recordall, Series 5000, Springfield, NJ). F-PHEA concentrations in perfusate were determined by area comparison of the eluted curves to that of the standard. Curves of logMW vs. elution volume, Ve, were constructed for each column using the integral-MWD method as described previously (9). Molecular weight distributions of absorbed material were determined from the calibration curves and the sample s chromatograph by curve summation (9). 

The critical weight of samples can be derived from the general condition of representativeness of sampling expressed by the null hypothesis H0 °totai = °anai which is tested by means of Fisher s F-test... 

Crystallization can be divided into three processes the primary nucleation process, the growth process, and the overgrowth process. The growth process is mainly controlled by the secondary nucleation mechanism. The steady (stationary) primary and secondary nucleation mechanisms of atomic or low molecular weight systems have been well studied since the 1930s by applying the classical nucleation theory (CNT) presented by Becker and Doring, Zeldovich, Frenkel and Turnbull and Fisher and so on [1-4]. 

Dissolve the protein to be modified at a concentration of 1-10 mg/ml in 0.1 M sodium phosphate, pH 7.4. NaCl may be added to this buffer if desired. For the modification of keyhole limpet hemocyanin (KLH Thermo Fisher) as described by Staros et al., 1986, include 0.9 M NaCl to maintain the solubility of this high-molecular-weight protein. If lower or higher concentrations of the protein are used, adjust the amounts of the other reactants as necessary to maintain the correct molar ratios. 

Rao, G.N., Haseman, J.K. and Edmondson, J. (1989). Influence of viral infections on body weight, survival, and tumor prevalence in Fisher 344 rats on two-year studies. Lab. Anim. Sci. 39 389-393. 

Number-average molar masses were determined using a vapor pressure osmometer (VPO) (Hitachi 117 Molecular Weight Apparatus) at 54.8 0.1°C in toluene (Fisher Scientific, certified A.C.S.) which was distilled from freshly crushed CaH2. The VPO apparatus was calibrated with pentaerythritol tetrastearate (Pressure Chemical). Gel permeation chromatographic (GPC) analyses were performed in tetrahydrofuran by HPLC (Perkin-Elmer 601 HPLC) using six y-Styragel columns (106, 105, 10l, 103, 500, and 100 A) after calibration with standard polystyrene samples. 

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