Estimates internal, precisely known

According to the pore size, zeolites are classified into small- (pore size up to 5 A), medium-(pore size 5-6 A), and large-pore types (pore size 7-8 A). Typical representatives of the different types are zeolite A, ZSM-5, and the faujasites (X and Y), respectively [5], According to the International Zeolite Association Website, about 190 different framework types of zeolites, zeolitic silicates and phosphates with precisely estimated structures are known to date (2010) [6],... 

The precision stated in Table 10 is given by the standard deviations obtained from a statistical analysis of the experimental data of one run and of a number of runs. These parameters give an indication of the internal consistency of the data of one run of measurements and of the reproducibility between runs. The systematic error is far more difficult to discern and to evaluate, which causes an uncertainty in the resulting values. Such an estimate of systematic errors or uncertainties can be obtained if the measuring method can also be applied under circumstances where a more exact or a true value of the property to be determined is known from other sources. 

Some assays not requiring high precision may not require addition of an internal standard. In these cases the analyte is extracted, and a known proportion of the extract injected. The amount of analyte in the aliquot can be estimated by comparison with the calibration curve. Such assays can be used for simple procedures requiring identification of analyte above a certain concentration where absolute concentration measurement is not required. Most assays will require internal standard to be added. 

Note 6. Combining the inequality constraint 0] with known Internal Poisson variance has been used by Guinn for total variance estimation in activation analysis ( 2), by Donahue (88) for the same purpose in accelerator mass spectrometry, by Heydorn (18.89) for the analysis of precision of gamma ray spectrum analysis, and by Currie ( ) for optimal weighting in counting experiments. The variance weighted t approximation derives from work by Cochran (90). Cochran s work, however, applied to a somewhat different model than used here. The statistical properties of this extension of his technique have not been studied. 

Internal, i.e., within department, quality control utilizing material of known concentration is used to assess the precision and bias of the assay. Inadequate analytical performance in internal schemes will result in rejection of the results from the analyzed samples. Performance criteria may simply be assessed as >2 standard deviations from the mean or by more complex bias and imprecision estimates such as Westgard rules. Rejection of quality control may require analyses to be rejected, corrective action to be taken, and the analyses repeated. 

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