Topic
Calibration curve
About: Calibration curve is a research topic. Over the lifetime, 6552 publications have been published within this topic receiving 95128 citations.
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Patent•
07 Jul 1982
TL;DR: In this article, an automatic chemical analyzer performs calibration by comparing a measured value obtained by measuring a reaction solution, obtained by reacting a sample with a reagent, with a calibration curve corresponding to the analysis item.
Abstract: An automatic chemical analyzer performs calibration by comparing a measured value obtained by measuring a reaction solution, obtained by reacting a sample with a reagent, with a calibration curve corresponding to the analysis item. In the apparatus, a desired number of analysis items and calibration intervals corresponding to the analysis items are set by an input device, and stored in the memory. A control device has a counting device, and checks if the calibration interval stored in the memory has elapsed for each analysis item so as to supply calibration alarm data and/or calibration indication data in accordance with the checking result and upon interlocking with the counting device. A display displays at least one of the above data.
118 citations
TL;DR: The Integrated Calibration Index is described, motivated by Harrell's Emax index, which is the maximum absolute difference between a smooth calibration curve and the diagonal line of perfect calibration, which can be interpreted as weighted difference between observed and predicted probabilities.
Abstract: Assessing the calibration of methods for estimating the probability of the occurrence of a binary outcome is an important aspect of validating the performance of risk-prediction algorithms. Calibration commonly refers to the agreement between predicted and observed probabilities of the outcome. Graphical methods are an attractive approach to assess calibration, in which observed and predicted probabilities are compared using loess-based smoothing functions. We describe the Integrated Calibration Index (ICI) that is motivated by Harrell's Emax index, which is the maximum absolute difference between a smooth calibration curve and the diagonal line of perfect calibration. The ICI can be interpreted as weighted difference between observed and predicted probabilities, in which observations are weighted by the empirical density function of the predicted probabilities. As such, the ICI is a measure of calibration that explicitly incorporates the distribution of predicted probabilities. We also discuss two related measures of calibration, E50 and E90, which represent the median and 90th percentile of the absolute difference between observed and predicted probabilities. We illustrate the utility of the ICI, E50, and E90 by using them to compare the calibration of logistic regression with that of random forests and boosted regression trees for predicting mortality in patients hospitalized with a heart attack. The use of these numeric metrics permitted for a greater differentiation in calibration than was permissible by visual inspection of graphical calibration curves.
117 citations
TL;DR: In this article, a discussion is devoted to the experimental conditions which influence the reproducibility of the measured signal and give rise to systematic errors, e.g., charging effects, matrix effects, selective sputtering and mass-dependent transmission, etc.
Abstract: Quantitative analysis in general aims at determining the value of a selected physical or chemical property of a given sample. With SIMS, in particular, the parameters to be determined are the concentration of a given element and also its distribution, both in depth and along the surface. Every measurement is affected by a given overall uncertainty due to statistical fluctuations in the measured signal and to systematic errors related to the experimental conditions. A discussion is devoted to the experimental conditions which influence the reproducibility of the measured signal and give rise to systematic errors, e.g. charging effects, matrix effects, selective sputtering and mass-dependent transmission, etc. The various methods used to derive the desired elemental concentration and its distribution in the sample from the raw measured data are evaluated, namely the use of calibration curves, relative sensitivity factors, fitting parameter methods and first-principle methods. Finally, the question is considered of how representative is the value determined from the (usually small) volume with respect to the composition of the bulk of the sample (sampling error).
115 citations
TL;DR: A robust flow injection (FI) on-line liquid-liquid extraction (LLE) preconcentration/separation system associated with a newly designed gravitational phase separator, coupled to flame atomic absorption spectrometry (FAAS) was developed and offered good performance characteristics.
115 citations
TL;DR: In this paper, three synthetic calibration solutions were used for the analysis of three silicate reference materials (BCR-2G, ATHO, and NIST 610) for laser-generated aerosols.
Abstract: For more than a decade liquid calibration has been proposed and selectively applied as a calibration strategy for laser-generated aerosols. However, matrix independent calibration is not a well-accepted technique for quantification in direct solid analysis using LA-ICP-MS. In this study three synthetic calibration solutions were used for the analysis of three silicate reference materials (BCR-2G, ATHO, and NIST 610). The calibration solutions were introduced into the ICP using an Aridus liquid sample introduction system with aerosol desolvation, while argon was used as the carrier gas. A 193 nm ArF excimer laser ablation system generated sample aerosols using helium as carrier gas. The argon carrier gas containing the solution nebulization aerosols was mixed, using a sheath gas adaptor in front of the ICP, with the laser aerosol carried in helium. Two different calibration strategies were applied for the multielement quantification of three geological reference materials. The first calibration technique used internal standardization with Ca as the internal standard. The second approach used synthetic calibration solutions containing all major, minor, and trace elements, in which the concentration ratios and concentrations of the elements were known. A normalization algorithm was used which calculated the sum of all of the determined element concentrations as oxides to 100%. The data shown for Ca indicate that both procedures are well suited for multi-element determinations. The 100% oxide normalization strategy allowed the calculation of the Ca concentration based on the total matrix used as internal standard. This Ca concentration was then used for the determination of the trace element composition of the sample. The advantage of this calibration is the possibility of element analysis in silicates without knowing the element concentration of at least one internal standard element prior to analysis. However, this study also shows that the composition of the solution used for the calibration can lead to losses of some elements during the desolvation process in the Aridus or during aerosol transfer to the ICP, which will be shown for Cu.
115 citations