Cross-checking Results

The development and standardization of reliable test procedures requires an ample supply of well-characterized reference materials. These samples are used for round-robin tests by participating laboratories in the method development. A reliable set of reference materials are available from the National Bureau of Standards. These special reference materials are described by Haines in this symposium series. The Bureau has packaged the materials in an appropriate size and secure container. Producer and user laboratories have these reference materials available to cross-check results and resolve differences in specification analyses. These reference standards are available at a reasonable cost. 

The cross-check results obtained on both procedures suggest that either the CRA-63 or HGA-70 procedure will provide reliable and accurate analysis of petroleum for trace levels of beryllium and there should be no significant difficulties in establishing these methods in other laboratories. 

The low cross-section of the reaction of I(n,p) I with fast neutrons (cf Table 2.3) and a low abundance of neutrons with energies higher than 9MeV, which are needed for this reaction, in the neutron spectrum of a nuclear reactor result in a detection limit which is not sufficient for iodine determination in most types of foodstuffs, even if an RNAA procedure is applied. However, this reaction, which is completely independent in relation to the reaction of I(n, ) I with thermal and epithermal neutrons may be useful for cross-checking results in analysis of foodstuff samples with higher iodine contents, using the so-called self-verification principle in NAA (Byrne and Kucera, 1997). Detection limits of various NAA modes, which were achieved in the authors laboratory are compared in Table 2.4. 

After completely evaluating the chart, cross-check results with the event and causal factors chart and change analysis. Reconcile any differences, use all three tools to aid in writing the formal accident report, and be careful to provide findings, conclusions, and recommendations (backed up with evidence) for each factor deemed to be less than adequate. 

Cappon and Crispin Smith O evaluated the accuracy and precision of the method by analyzing different sample types fortified with mercuric chloride and methylmercuric chloride (Table 20). Mean deviation and relative accuracy averaging 3.2 and 2,2% respectively, were observed. They also cross checked results obtained by their method and by an atomic absorption procedure. Results obtained on samples by both methods are given in Table 21, There is good agreement between the two methods for samples methyl-, ethyl-, and inorganic mercury, and this is expressed in terms of GC/AA ratios. 

Steric FFF, used for micron size particles, is not only fast and accurate but it has the overriding advantage of allowing the physical collection of narrow size fractions. With such fractions, one can use microscopy and other methods to confirm the accuracy of calibration and examine variations in particle shape, density, chemical composition, etc., as a function of size. These fractions provide an optional "window" for cross checking results and extending the characterization of particulate materials beyond that commonly available. 

Cross-checking and interpreting the various results obtained against predetermined specifications and norms... 

The approach taken by the authors of the two methods is fundamentally different, and this provides a useful cross-check on the predicted values. Judgement must always be used when using predictive methods in design, and it is always worthwhile trying several methods and comparing the results. 

Hence, for reactions of monodentate ligands (or for multidentate ligands in certain cases - see later), /CML can be evaluated solely in terms of the results from kinetic measurements. This has frequently been used as a cross-check of values determined by thermodynamic techniques. Alternatively, JCML values obtained by the latter means have been used in conjunction with either kt or kd to obtain the remaining constant. 

The final points to pick up here are that care needs to be exercised at every stage of the work. Even then, simple errors may creep into the most carefully made measurements, but these can usually be spotted by cross-checking. Poorly matching results of duplicate analyses may well be a clue to problems in the whole measurement system. A key part of any work is to tidy everything away afterwards, and deal yourself with any hazards you may have created. In brief, leave everything as you would hope to find it. 

In certain specific cases tha accuracy of a result may be cross-checked by performing another analysis of the same substance by an altogether radically different method. 

Note Although similarity searches generally provide useful search results, it is always necessary to cross check the hits from the database. Even the highest score hit can be wrong. Some interpretational skills will be advantageous. .. 

Since the combination operation performs all intersections between the focal elements of each refined belief assignment, this method of refinement/ combination/ coarsening guarantees that all the possible cross-checks have been done. The focal elements resulting of the projection have the highest level of details allowed by the whole information put in the decision system. This means that if there was no crosschecking relation for a sensor, then the only focal element would be the one of total doubt, i.e. 17. ... 

All the samples should be analyzed for 40 elements (by ICP-MS) as well as gold (Fire assay) and the results should be cross checked by several methods. 

Acyclic carbohydrates with two alkyl chains have been studied in detail in the case of dialkyldithioacetals 9. It is one of the more complete series whose results have been cross-checked and compiled [43]. Their liquid crystalline properties were compared with those of dodecyl a- and -D-glucofuranosides [50] depending on their structures, they form either hexagonal disordered columnar phases or a new rectangular columnar phase [77]. 

While UNODC is not in a position to verify the accuracy of all individual city results, there are still possibilities to undertake some broad plausibility checks, cross-checking the waste-water results with information from other sources. 

As a cross-check of this result a spectral simulation with a PT of prolate symmetry is given in Fig. 4c, The difference to the other traces is seen in the missing K-type recurrences. The occurrence of K-type transients in fs DFWM spectra can be rationalized by significant components of the polarizability tensor perpendicular to the symmetric top axis. Finally, it was demonstrated that the types and intensities of recurrences in fs DFWM spectra are a sensitive measure for the symmetry of the PT of the corresponding molecule. 

These various expressions show the flexibility of the competitive method. Any of the expressions (1), (3)-(5) can be used to evaluate kx/k2 but the experimental conditions must be in accord with the underlying assumptions. It is significant that consistent results were obtained by the use of different types of measurements (and therefore of the alternative expressions given above) and also by interchanging reaction partners in order to cross-check the relative values. 

Since dynamic mechanical tests measure the response of a material to an applied stress at different temperature and frequency, they measure the transition of the material from glassy to leathery to rubbery state. If the frequency is kept constant and low (about one cycle/sec), the results are related to measurements of transition by other techniques. Thus, some cross-checking is possible. 

Sometimes, using more than one program to cross-check the results is advisable. And results should be corroborated with experimental information wherever possible. 

For cleaning validation, the cleaning process must be defined and the parameters described in writing. The limits and test procedures must be described. The process is then run and the records cross-checked against the parameters. The results are then evaluated. This process is repeated three times to prove the reproducibility of the process. 

The early workers were severely hampered, of course, by the considerable difficulty of carrying out, for even small systems, the prescriptions of VB theory with sufficient accuracy to assess their merit. Except for H2 and perhaps a few other molecules and ions, no really accurate VB calculations were possible, and, to make progress, most workers had to resort to many approximations. There thus arose a series of generalizations and conclusions that were based upon results of at least somewhat uncertain value. In their review of early results, Van Vleck and Sherman[3] comment upon this point to the effect that a physical or chemical result was not to be trusted unless it could be confirmed by several calculations using different sorts of approximations. It is perhaps only to be expected that such cross checking was rather infrequently undertaken. 

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