Reproducibility/repeatability

Precision is a measure of the spread of data about a central value and may be expressed as the range, the standard deviation, or the variance. Precision is commonly divided into two categories repeatability and reproducibility. Repeatability is the precision obtained when all measurements are made by the same analyst during a single period of laboratory work, using the same solutions and equipment. Reproducibility, on the other hand, is the precision obtained under any other set of conditions, including that between analysts, or between laboratory sessions for a single analyst. Since reproducibility includes additional sources of variability, the reproducibility of an analysis can be no better than its repeatability. 

The determination of precision can divided into three categories, namely repeatability, intermediate precision, and reproducibility. Repeatability, or intraassay within-day precision, is determined when the analysis is performed in one laboratory by one analyst, using one definite piece of equipment, and is performed within one working day. Intermediate precision is obtained when the analysis is performed within a single laboratory by different analysts over a number days or weeks, using different equipment, reagents, and columns. Reproducibility represents the... 

Over the last several years, the number of studies on application of artificial neural network for solving modeling problems in analytical chemistry and especially in optical fibre chemical sensor technology, has increase substantially69. The constructed sensors (e.g. the optical fibre pH sensor based on bromophenol blue immobilized in silica sol-gel film) are evaluated with respect to prediction of error of the artificial neural network, reproducibility, repeatability, photostability, response time and effect of ionic strength of the buffer solution on the sensor response. 

The repeatability and reproducibility values have important implications for quality. As the demand for clear product specifications, and hence control over product consistency, grows, it is meaningless to establish product specifications that are more restrictive than the reproducibility/repeatability values of the specification test methods. 

Sufficiency of disclosure is a more straightforward requirement. Sufficient technical detail must be provided in the patent application such that somebody of ordinary technical skill in the area could reproduce/repeat the innovation. Utility or industrial applicability is the last major prerequisite to patenting. This simply means that the innovation must have some applied use. 

Two types of precision are usually distinguished, namely the repeatability and the reproducibility. Repeatability is the precision obtained in the best possible circumstances (same analyst, one instrument, within one day when possible) and reproducibility under the most adverse possible circumstances (different laboratories, different analysts, different instruments, longer periods of time, etc.). Reproducibility can be determined only with interlaboratory experiments. Intermediate situations may and do occur. They are for instance defined in terms of M-factor-different intermediate precision measures, where M is one, two, three or even higher [8,9]. In this definition M refers to the number of factors that are varied to make the estimation. The most likely factors to be varied are time, analyst and instrument. According to this terminology, one estimates e.g. the time-and-analyst-different intermediate precision measure (M=2), when the precision is determined by measuring a sample over a longer period of time in one laboratory by two analysts with one instrument. 

Microbiological inhibition tests are generally considered to be an unreliable method for detecting residues of antimicrobial agents in meat. The development of more specific, sensitive, reproducible, repeatable and robust chemical-based methods of analysis will offer methods capable of detecting residues previously undetectable by biological assays. 

The ICH has broadened and redefined these terms to more accurately describe the method s ability to reproducibly generate analytical results. Precision is defined as a combination of repeatability, intermediate precision, and reproducibility. Repeatability is system precision, as defined previously. Intermediate precision includes multiple analyses by multiple analysts on different days using different equipment within a given laboratory. This is only the first step in demonstrating the ruggedness of the method. 

Precision (1) Repeatability (2) Reproducibility Repeat analysis of either a CRM or a homogenous sample Several laboratories carry out repeat analyses of either a CRM or a homogenous sample... 

Any new method to be used in the laboratory should be rigorously tested, to ensure that reproducibility, repeatability and robustness comply with internationally... 

The influence of simultaneous thermal and chemical cycling on commercial three-way catalysts has been examined after ageing in a specifically designed automated laboratory bench. For all cycles tested, reproducing repeated fiiel cutoff procedures between two temperatures (850°C-850°C, cycle 1 850°C-950°C, cycle 2 850°C-1050°C, cycle 3), X-ray diffraction evidences the formation of platinum/rhodium alloys only when the atmosphere cycle comprises a reducing step. Evaluation of the rhodium concentration in alloyed phases suggests that some rhodium remains unalloyed in catalysts. 

Scope. The scope of assay validation is to assess the essential test method performance characteristics of accuracy, reproducibility, repeatability, linear-ity, and limit of quantitation/detection [41]. A test method is evaluated for its readiness for assay validation against the following criteria (1) description of the test basis and scientific purpose, (2) case for relevance, (3) proposed practical application,... 

Precision - integration, particularly at low sample amounts, may be difficult and an assessment of the precision of the experiment is needed. As alluded to above there are three levels of precision testing repeatability, intermediate precision and reproducibility. Repeatability expresses the precision under the same operating conditions over a short interval of time. This is frequently the only precision information provided in literature reports. Intermediate precision expresses within-laboratory variations across different days, different analysts, different equipment, etc. and it is a key indicator of how an assay will perform under real conditions. Reproducibility expresses the precision between laboratories and typically only becomes important if a method is transferred between laboratories - for example, from an R D site to a manufacturing facility. 

For abbreviation purposes, lefs define S(test) as the standard deviation due to a test method. S(test) should always be qualified to identify whether this estimate is for reproducibility, repeatability, or any other set of variation components. 

Intra-assay precision to establish reproducibility/ repeatability of an assay by comparing replicates within a single run... 

ISO 5725 [5] defines precision as the closeness of agreement between mutually independent test results obtained under stipulated conditions , and identifies two aspects of it, which it terms repeatability and reproducibility . Repeatability is superficially similar to what is here called precision, being a measure of the agreement between replicate results obtained by a single operator on the same sample, using the same apparatus in the same laboratory over a short period of time. But this concept seems to be based on the assumption that all operators are equal, and they are manifestly not. Reproducibility is a measure of the level of agreement between the results obtained by different operators on the... 

Other significant aspects of SPME techniques are reproducibility, repeatability, fiber stability, and the possibility of quantitative determinations. 

Many silicone coloring systems were hypothetically supposed to match accurately the entire human skin colors and cover a wide skin color range [4], However, no system until today has such two features. The major concern in silicone coloring is how to find simple procedures that are, reproducible, repeatable, pigment stable [5], and provide real-color skin matching colors. The most commonly used devices in measuring and recording skin color are... 

Detection of precipitins uses different methods, depending on the study. Besides the intrinsic problems inherent with each technique (standardisation, reproducibility, repeatability), this variety makes comparison between studies difficult. Rough methods seem preferable to sophisticated uninterpretable methods with several unspecific signals. 

This evaporation spike can also be reproduced repeatedly by tapping the Uquid container at fairly lengthy intervals. Frequently, the flow meter goes off-scale during the spike, but rapidly came back on scale towards the previous reading. Rocking the container so as to cause the liquid to slosh, will also create a boil-off spike. 

Symbols and general abbrevs. c concentration/content, Eacdadsidep accumulation/adsorption/deposition/potential, el. electrode, In(R) interference (ratio), LOD limit of detection, LR linear range, M molar concentration (mol per litre), min minute(s), RR reproducibility/repeatability, sat. saturated, SE supporting electrolyte, SS sample solution, tacc/dep accumulation/deposition time... 

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