scholarly journals Components of Total Measurement Error for Hemoglobin A1c Determination

2001 ◽  
Vol 47 (10) ◽  
pp. 1851-1853 ◽  
Author(s):  
George Phillipov ◽  
Patrick J Phillips
Keyword(s):  
Measurement Error ◽  
Hemoglobin A1c ◽  
Total Measurement Error

scholarly journals Tilt error in cryospheric surface radiation measurements at high latitudes: a model study

2016 ◽  
Vol 10 (2) ◽  
pp. 613-622 ◽  
Author(s):  
Wiley Steven Bogren ◽  
John Faulkner Burkhart ◽  
Arve Kylling
Keyword(s):  
Measurement Error ◽  
Total Error ◽  
Surface Radiation ◽  
Cloud Optical Depth ◽  
Model Study ◽  
Tilt Error ◽  
Total Measurement Error ◽  
Spectral Ranges ◽  
Radiation Measurements

Abstract. We have evaluated the magnitude and makeup of error in cryospheric radiation observations due to small sensor misalignment in in situ measurements of solar irradiance. This error is examined through simulation of diffuse and direct irradiance arriving at a detector with a cosine-response fore optic. Emphasis is placed on assessing total error over the solar shortwave spectrum from 250 to 4500 nm, as well as supporting investigation over other relevant shortwave spectral ranges. The total measurement error introduced by sensor tilt is dominated by the direct component. For a typical high-latitude albedo measurement with a solar zenith angle of 60°, a sensor tilted by 1, 3, and 5° can, respectively introduce up to 2.7, 8.1, and 13.5 % error into the measured irradiance and similar errors in the derived albedo. Depending on the daily range of solar azimuth and zenith angles, significant measurement error can persist also in integrated daily irradiance and albedo. Simulations including a cloud layer demonstrate decreasing tilt error with increasing cloud optical depth.

scholarly journals An Improved STEM/EDX Quantitative Method for Dopant Profiling at the Nanoscale

2020 ◽  
Vol 26 (1) ◽  
pp. 76-85
Author(s):  
Raghda Makarem ◽  
Filadelfo Cristiano ◽  
Dominique Muller ◽  
Pier Francesco Fazzini
Keyword(s):  
Measurement Error ◽  
Mass Density ◽  
Estimation Procedure ◽  
Observation Time ◽  
Test Structure ◽  
Profile Measurement ◽  
Rutherford Back Scattering ◽  
Dopant Profiling ◽  
Absorption Correction ◽  
Total Measurement Error

AbstractIn this paper, an improved quantification technique for STEM/EDX measurements of 1D dopant profiles based on the Cliff-Lorimer equation is presented. The technique uses an iterative absorption correction procedure based on density models correlating the local mass density and composition of the specimen. Moreover, a calibration and error estimation procedure based on linear regression and error propagation is proposed in order to estimate the total measurement error in the dopant density. The proposed approach is applied to the measurement of the As profile in a nanodevice test structure. For the calibration, two crystalline Si specimens implanted with different As doses have been used, and the calibration of the Cliff-Lorimer coefficients has been carried out using Rutherford Back Scattering measurements. The As profile measurement has been carried out on an FinFET test structure, showing that quantitative results can be obtained in the nanometer scale and for dopant atomic densities lower than 1%. Using the proposed approach, the measurement error and detection limit for our experimental setup are calculated and the possibility to improve this limit by increasing the observation time is discussed.

scholarly journals Tilt error in cryospheric surface radiation measurements at high latitudes: a model study

2015 ◽  
Vol 9 (4) ◽  
pp. 4355-4376 ◽  
Author(s):  
W. S. Bogren ◽  
J. F. Burkhart ◽  
A. Kylling
Keyword(s):  
Measurement Error ◽  
Solar Zenith Angle ◽  
Total Error ◽  
Surface Radiation ◽  
Model Study ◽  
Tilt Error ◽  
Total Measurement Error ◽  
Spectral Ranges ◽  
Radiation Measurements

Abstract. We have evaluated the magnitude and makeup of error in cryospheric radiation observations due to small sensor misalignment in in-situ measurements of solar irradiance. This error is examined through simulation of diffuse and direct irradiance arriving at a detector with a cosine-response foreoptic. Emphasis is placed on assessing total error over the solar shortwave spectrum from 250 to 4500 nm, as well as supporting investigation over other relevant shortwave spectral ranges. The total measurement error introduced by sensor tilt is dominated by the direct component. For a typical high latitude albedo measurement with a solar zenith angle of 60°, a sensor tilted by 1, 3, and 5° can respectively introduce up to 2.6, 7.7, and 12.8 % error into the measured irradiance and similar errors in the derived albedo. Depending on the daily range of solar azimuth and zenith angles, significant measurement error can persist also in integrated daily irradiance and albedo.

scholarly journals VISCOMETRY OF NANODISPERSE MAGNETIC LIQUIDS AND LUBRICATING OILS. 2. METROLOGICAL ANALYSIS OF A DEVICE FOR RHEOLOGICAL STUDIES OF MAGNETIC NANODISPERSE LIQUID MEDIA

2021 ◽  
pp. 56-64
Author(s):  
Александр Николаевич Болотов ◽  
Ольга Олеговна Новикова ◽  
Владимир Валентинович Мешков
Keyword(s):  
Measurement Error ◽  
Systematic Error ◽  
Metrological Analysis ◽  
Improve Design ◽  
Measuring Cylinder ◽  
Methodological Errors ◽  
Magnetic Liquids ◽  
Total Measurement Error ◽  
Experimental Values ◽  
Rotary Viscometer

Проведен анализ основных источников методических погрешностей магнитного ротационного вискозиметра, позволивший усовершенствовать конструкцию и исключить критические режимы исследований. Теоретическая оценка систематической погрешности прибора показала, что значение относительной ошибки измерений можно довести до значения менее 1%. Наибольший вклад в систематическую погрешность прибора вносит нестабильность температурного режима исследуемой наножидкости и неточность определения высоты слоя жидкости, контактирующего с измерительным цилиндром. Измерение вязкости эталонных жидкостей на магнитном вискозиметре показало, что экспериментальные значения незначительно, примерно на 0,9% завышены. Тарировка прибора на различных эталонных жидкостях позволила снизить суммарную ошибку измерений до десятых долей процента. Магнитный ротационный вискозиметр может найти применение при нестандартных научных исследованиях структуры и реологических характеристик наножидкостей, для оперативного контроля процессов синтеза магнитных жидкостей и аттестации магнитных наножидкостей, предназначенных для технического применения. An analysis is carried out of the main sources of methodological errors of the magnetic rotary viscometer. The analysis allowed to improve design and to eliminate critical modes of the research. Theoretical evaluations of the systematic error of the device showed that the value of the relative measurement error can be brought to a value of less than 1%. The greatest contribution to the systematic error of the device is made by the instability of the temperature regime of the nanofluid under study and by the inaccuracy of determining the height of the liquid layer in contact with the measuring cylinder. The measurement of the viscosity of the reference liquids on the magnetic viscometer showed that experimental values are slightly, by about 0.9% overestimated. Calibration of the device on various reference liquids allowed reducing the total measurement error down to tenths of a percent. The magnetic rotary viscometer can be used in non-standard scientific studies of the structure and rheological characteristics of nanofluids, for operational control of the processes of synthesis of magnetic liquids and certification of magnetic nanofluids intended for technical use.

Benefits from Computerized Adaptive Testing as Seen in Simulation Studies

1999 ◽  
Vol 15 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Lutz F. Hornke
Keyword(s):  
Measurement Error ◽  
Computerized Adaptive Testing ◽  
Test Procedure ◽  
Adaptive Testing ◽  
Parameter Estimates ◽  
Simulation Studies ◽  
Computerized Adaptive Test ◽  
Item Banks ◽  
Item Parameters ◽  
General Reliability

Summary: Item parameters for several hundreds of items were estimated based on empirical data from several thousands of subjects. The logistic one-parameter (1PL) and two-parameter (2PL) model estimates were evaluated. However, model fit showed that only a subset of items complied sufficiently, so that the remaining ones were assembled in well-fitting item banks. In several simulation studies 5000 simulated responses were generated in accordance with a computerized adaptive test procedure along with person parameters. A general reliability of .80 or a standard error of measurement of .44 was used as a stopping rule to end CAT testing. We also recorded how often each item was used by all simulees. Person-parameter estimates based on CAT correlated higher than .90 with true values simulated. For all 1PL fitting item banks most simulees used more than 20 items but less than 30 items to reach the pre-set level of measurement error. However, testing based on item banks that complied to the 2PL revealed that, on average, only 10 items were sufficient to end testing at the same measurement error level. Both clearly demonstrate the precision and economy of computerized adaptive testing. Empirical evaluations from everyday uses will show whether these trends will hold up in practice. If so, CAT will become possible and reasonable with some 150 well-calibrated 2PL items.

Predictors of diabetic ketoacidosis hospitalizations and hemoglobin A1c among youth with Type 1 diabetes.

2019 ◽  
Vol 38 (7) ◽  
pp. 577-585 ◽  
Author(s):  
Katherine Semenkovich ◽  
Kristoffer S. Berlin ◽  
Rachel L. Ankney ◽  
Kimberly L. Klages ◽  
Mary E. Keenan ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Diabetic Ketoacidosis ◽  
Hemoglobin A1c
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