Relative standard deviation factors that increase

Reproducibility. Reproducibility is a third factor that depends primarily on recovery. As a general rule, reproducibility improves as recovery increases. For the majority of compounds for which the recovery is greater than 40%, the reproducibility will be on the order of 2 - 8% relative standard deviation (RSD). This number is strongly affected by column resolution, however, since many foods samples tend to give complicated chromatograms. As the recovery drops below 40% the reproducibility rapidly deteriorates. For very volatile compounds, the purge efficiency... 

The interlaboratory results obtained from the analysis of defined standard solutions, but also from the analysis of sediment extracts prepared either by the coordinator of the study or by the participants themselves, also provide a measure of the variation between laboratories. The results show that the interlaboratory reproducibility ranges from 6.5% for the defined dioxin sample to 27.9% for the sediment sample extracted by the participants themselves. As was mentioned before, the reproducibility for this last sample is relatively high and most presumably due to the introduction of extra handlings (extraction and cleanup) to the total procedure. In addition, the fact that not all the participants had prior experience with the extraction protocol to be used could have added to the increase in variability of the process. Furthermore, the dilution factor was not dictated. This also introduces a certain degree of variation. For the reproducibility of the DR CALUX bioassay itself and not caused by differences in operating extraction conditions, the maximum variation between laboratories was observed to be 18.0%. The results for the sediment extract samples can also be used to estimate the method variability for extracts, that is, based on samples of unknown composition. Again, given the intra-as well as the interlaboratory variations observed in this study, it appears justified to conclude that the standard deviation of the means provides a reasonable estimate of the method variability, based on the overall aver-... 

Note that the standard errors in the rate constants (kx = 2.996 0.005 x 10-3 s 1 and 2 = 1.501 0.002 x 10 3 s ) are delivered in addition to the standard deviation (<7y = 9.991 x 10 3) in Y. The ability to directly estimate errors in the calculated parameters is a distinct advantage of the NGL/M fitting procedure. Furthermore, even for this relatively simple example, the computation times are already faster than using a simplex by a factor of five. This difference dramatically increases with increasing complexity of the kinetic model. 

We study first the correlation between volatility behaviors of the 14 equity indexes. The study is based on the relative periodic standard deviation STD (with 1 period=3 months) of different equities with respect to the STD of their log-return distribution for the 20 years period. For 9 over 14 indexes we found a strongly correlated STD behavior i.e. the relative STD increases (and decreases) appear simultaneously for this 9 indexes, which shows that the volatility of daily returns distribution may be related to an external factor that will be called the environment state factor or ES factor . We suggest that a sub-period ES can be represented by a simple Markov Chain of three states. The states that represent the three different states of the ES factor are defined by the following ... 

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