Assessment methods

Any effort to improve a model s performance must start with a good assessment of its current performance. 

There are several items that can help provide this assessment. 

With the above information in hand, it is then possible to consider different improvement schemes. 

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A simple, quahtative method is the skin stripping technique (322) which strips off a sampling from the skin with ceUophane tape. Methods have been developed (330,331) in which organisms on the hands ate transferred to gloves and sampled. These methods assess both immediate and persistent effects of antiseptics. In aH tests with antiseptics, suitable neutralizing chemicals for the antiseptics employed are necessary so that surviving bacteria may be recovered and counted. Some of these are lecithin, Lubrol W, Polysorbate, and sodium thiosulfate (322). 

Thermal Fixation Properties of Disperse Dyes on Polyester—Gotton. This method assesses the fixation properties of disperse dyes as a function of the time, temperature, dyestuff concentration, or presence and amount of auxiUary agents. The polyester—cotton fabric is padded and dried, the cotton dissolved in sulfuric acid and washed out of the blend, and the amount of dye on the polyester component assessed by either reflectance or measuring the optical density of a solution of dye obtained by extracting the dye with boiling chloroben2ene solvent. 

The types of analyses discussed in this section can be divided into two groups active matter and impurities. Several methods assess the anionic surfactant (active matter) content of the AOS product. These are particularly important since detergent performance is directly related to surfactant concentration. The different types of anionic active material are identified and quantified. 

Adequate precision and accuracy are only likely to be achieved if some standardization procedure is employed and the nature of this, internal or external standards or the method of standard additions, needs to be chosen carefully. If internal standardization procedures are adopted then appropriate compound(s) must be chosen and their effect on the chromatographic and mass spectrometry methods assessed. The ideal internal standard is an isotopically labelled analogue of the analyte but, although there are a number of commercial companies who produce a range of such molecules, these are not always readily available. An analytical laboratory is then faced with the choice of carrying out the synthesis of the internal standard themselves or choosing a less appropriate alternative with implications on the accuracy and precision of the method to be developed. 

Functions of Standards. Fluorescent standards can be used for three basic functions calibration, standardization, and measurement method assessment. In calibration, the standard is used to check or calibrate Instrument characteristics and perturbations on true spectra. For standardization, standards are used to determine the function that relates chemical concentration to Instrument response. This latter use has been expanded from pure materials to quite complex standards that are carried through the total chemical measurement process (10). These more complex standards are now used to assess the precision and accuracy of measurement procedures. 

Determination of appropriate measuring and analysis methods Assessment of standards and acceptable tolerances Interpretation of test results... 

The density functional methods assessed in this study (B3LYP, BLYP, and LDA) all perform much worse for the enthalpies of formation of the larger molecules in the G3/99 set. This is due to a cumulative effect in the errors for the larger molecules in this test set. The errors are found to be approximately proportional to the number of pairs of electrons in the molecules but the methods are not improved significantly when a higher-level correction such as that used in G2 or G3 theory is added the DFT methods. Further correction schemes may be necessary to improve the performance of density functional methods for large molecules. 

Depending on the details obtained from the method assessment above, there are several possible actions that could be considered for improving the performance of an existing calibration model ... 

Improved reference analysis If the method assessment reveals that the main source of model error comes from error in the reference analytical method used to generate the (y) calibration data, then efforts to improve the accuracy and precision of this method could prove to be very beneficial. 

Huikuri HV, Makikallio TH, Raatikainen MJ, et al. Prediction of sudden cardiac death appraisal of the studies and methods assessing the risk of sudden arrhythmic death. Circulation. Jul 8 2003 108(1) 110-115. 

Wildfong, P.L.D. Samy, A.-S. Corfa, J. etal., Accelerated fluid bed drying using NIR monitoring and phenomenological modeling Method assessment and formulation suitability /. Pharm. Sci. 2002, 91, 631-639. 

New Dosage Strengths, etc.), Older Products Already on the Market (Updating Methods, Assessing Process Changes). 178 References. 179... 

Portier, R.J. (1985) In ASTM STP 865. (Validat. Predict. Lab Methods Assess. Fate Eff. Contam. Aquat. Ecosyst.), pp. 14—30. 

Cooper, M. M., S. Sandi-Urena, and R. Stevens (2008a) Reliable multi-method assessment of metacognition use in chemistry problem-solving. Chem. Educ. Res. Pract. 9,18-24. 

Wildfong PLD, Sarny AS, Corfa J, Peck GE, Morris KR. Accelerated fluid bed drying using nir monitoring and phenomenological modeling method assessment and formulation suitability. J Pharm Sci 2002 9I(3) 631-9. 

Production control planning, preparation of materials, traceability and calibration, measurement equipment and methods, assessment of homogeneity and stability, data treatment and certification. 

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