Testing methods control variables

The sometimes contradictory results from different workers in relation to the elements mentioned above extends to other elements . Some of these differences probably arise from variations in test methods, differences in the amounts of alloying additions made, variations in the amounts of other elements in the steel and the differing structural conditions of the latter. Moreover, the tests were mostly conducted at the free corrosion potential, and that can introduce further variability between apparently similar experiments. In an attempt to overcome some of these difficulties, slow strain-rate tests were conducted on some 45 annealed steels at various controlled potentials in three very different cracking environments since, if macroscopic... 

Dissolution test data will be required in all cases (and for all strengths of product) for development and routine control and should be based on the most suitable discriminatory conditions. The method should discriminate between acceptable and unacceptable batches based on in vivo performance. Wherever possible Ph Eur test methods should be used (or alternatives justified). Test media and other conditions (e.g., flow through rate or rate of rotation) should be stated and justified. Aqueous media should be used where possible and sink conditions should be maintained. A small amount of surfactant may be added where necessary to control surface tension or for active ingredients of very low solubility. Buffer solutions should be used to span the physiologically relevant range—the current advice is over pH 1 6.8 or perhaps up to pH 8 if necessary. Ionic strength of media should be reported. The test procedure should employ six dosage forms (individually) with the mean data and a measure of variability reported. 

Early optimism about the possibility of in vitro-in vivo correlation was tempered by the need for a performance test that would yield reproducible results (10). Even though not necessarily correlated to bioavailability, dissolution requirements were seen as useful in controlling variables in formulation or processing. Thus, from the start, sources of variability in the results were seen as factors to be minimized in any proposed compendial method. 

There is an analysis of the results of the study adequate to assess the effects of the drug. The report of the study should describe the results and the analytic methods used to evaluate them, including any appropriate statistical methods. The analysis should assess, among other things, the comparability of test and control groups with respect to pertinent variables, and the effects of any interim data analyses performed. 

Standard test methods are useful only if they can be reproduced. It is important that the same results be measured by both the adhesive developer and the end user. It is also important that the results be reproducible with time and with different testing personnel. The accuracy and reproducibility of test results depend on the conditions under which the bonding process is performed. The following variables must be strictly controlled. 

Purpose. As biopharmaceutical products are large and complex molecules and no single test method is sufficient, product analysis uses multiple, different analytical methods strategically designed to be complementary with respect to selectivity and specificity [4, 27]. More sensitive test methods allow proof of greater removal of a putative risk factor [12], and the more key parameters that can be measured assure that process variability is understood and controlled [66]. However, it is important... 

The HCPHWT has been the traditional evaluation tool for antibacterial soap products in the United States. This is a controlled, clinical method with a historical database. Although it was intended to model in the healthcare setting, it has been used as the basis to support marketed claims for antibacterial soap products for both consumer and professional use. The above discussions demonstrate that the HCPHWT method does not provide control for many of the variables that can influence the performance of test products ( especially consumer products). Consequently, use of this test may not adequately evaluate the efficacy of products intended for use by consumers. A need exists for additional test methods specifically designed to evaluate consumer products while modeling real-world conditions. 

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