Equivalency testing

If a standard method is available, the performance of a new method can be evaluated by comparing results with those obtained with an approved standard method. The comparison should be done at a minimum of three concentrations to evaluate the applicability of the new method for different amounts of analyte. Alternatively, we can plot the results obtained by the new method against those obtained by the approved standard method. A linear regression analysis should give a slope of 1 and ay-intercept of 0 if the results of the two methods are equivalent. 

A validation method used to evaluate the sources of random and systematic errors affecting an analytical method. 

Partitioning of random error, systematic errors due to the analyst, and systematic error due to the method for (a) replicate analyses performed by a single analyst and (b) single determinations performed by several analysts. 

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Mg = sample mass used in a DIERS test or equivalent test, g dP/dt = pressure rise in test, psi/see T = maximum temperature in test, K... 

The C-5 sugar alcohols produced from the hydrolysis of hemicellulose are both xylitol and arabitol [6], Equivalence testing was performed with Ni/Re catalyst in the batch reactor to verily similar performance between xylitol and arabitol feedstocks. The operating conditions were 200°C and 8300kPa H2 using the procedure outlined in section Catalyst Screening section. 

The alternative Instrument used was a Portable Continuous Aerosol Monitor (PCAM) manufactured by ppm, Inc., and dust concentrations measured with the PCAM were 5-15% lower than values obtained with standard vertical elutriators. Calculations and examples for TWA exposures, equivalency tests, and vertical elutriator coefficients of variation are included. 

Figure 9. Schematic of PC AM equivalency testing rig showing the relationship of large vertical elutriators to PC AM small vertical elutriator.

A complementary approach is to conduct the assays under high-throughput automated conditions. This can be either through the miniaturization of assays, that is, 96-384 plates and if possible 1536, or through the use of alternative assay technologies (e.g., microfluidics). Both scenarios require studies of equivalency testing and backwards compatibility with previous methods and results. 

In this chapter we describe characteristic validation procedures of the Heavy Metals Limit Test in the Japanese Pharmacopoeia (JP) [1]. Although an equivalent test is commonly listed in both the United States Pharmacopoeia and the European Pharmacopoeia, there are differences in the color reagents and conditions of sample preparation of the JP procedure. Heavy metals are defined in the JP as poisonous metallic impurities such as Pb, Bi, Cu, Cd, Sn, and Hg that form colored colloidal precipitates with sodium sulfide TS in a slightly acidic solution of pH 3 to 4. The level is expressed as the equivalent quantity of lead. 

To cover the widest range of frequencies in a single test, a controlled-stress device operating in a controlled-strain mode, or the equivalent test for a controlled-strain device, will provide the optimal configuration because the stresses or strains, respectively, are boosted to stay within the dynamic range of the instrument. If the results for LVE behavior have not been generated, then a fixed strain of 0.1% to 1.0% is likely to be adequate. As before, lower stresses should be used if the sample is a dispersion or emulsion, and higher stresses should be used if it is polymeric in form. 

It should be noted that if a solid tech Na azide is used as a starting material for the above test it is necessary to remove the carbonates prior to adding NaNOa. This can be done by dissolving the sample in distd w and neutralizing the soln with HC1, using methyl-orange, methyl-yellow or equivalent test paper... 

The Tar—Tar sequence as well as the A-form RNA and B-form DNA equivalents of Tar—Tar (see Fig. 20.3) do not contain palindromes. However, we have data from multiple independent simulations and the analysis of Ponomarev et al. can be repeated using data from pairs of simulations. The equivalent test is to compare the residue-resolved ion-contact distributions between replicate trajectories. Such comparisons are a stringent test if each simulation was separately initialized with randomized ion starting positions and velocities. The PCCs for the A-form RNA simulations are shown in Fig. 20.4. Error bars denote the standard errors across the six possible pairwise comparisons across four independent trajectories, each of... 

Equivalency testing. Once the method has been developed, it is compared to similar existing methods. Statistical tests are used to determine if the new and established methods give equivalent results. Typical tests include Student s Most for a comparison of the means and the / -test for a comparison of variances. 

Traditional statistical testing tends to focus on attempts to demonstrate that a measured value changes according to what treatment is used. This is called difference testing . However, there are occasions when we want to show that a measured value does not change. This, we would call equivalence testing . Typical cases where we might wish to demonstrate equivalence include ... 

Equivalence testing is designed to show that there are no differences big enough to be worth worrying about. To demonstrate equivalence, the whole of the 95 per cent Cl for the size of any difference should lie entirely within the equivalence zone. 

An example of equivalence testing - comparing two propranolol formulations... 

Difference vs equivalence testing. Same test - different interpretations... 

Notice that difference and equivalence testing use exactly the same statistical calculation. In both cases, a two-sample /-test is used to generate a 95 per cent Cl for difference. It is the interpretation that differs. 

Equivalence testing (as described) would form a necessary part of any demonstration that two analytical methods were interchangeable, but it would not be sufficient alone. If you need to tackle this problem, consult a specialized text. 

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