Error Adjustment Research Articles

Adjustment of recall errors in duration data using SIMEX

It is widely accepted that due to memory failures retrospective survey questions tend to be prone to measurement error. However, the proportion of studies using such data that attempt to adjust for the measurement problem is shockingly low. Arguably, to a great extent this is due to both the complexity of the methods available and the need to access a subsample containing either a gold standard or replicated values. Here I suggest the implementation of a version of SIMEX capable of adjusting for the types of multiplicative measurement errors associated with memory failures in the retrospective report of durations of life-course events. SIMEX is a method relatively simple to implement and it does not require the use of replicated or validation data so long as the error process can be adequately specified. To assess the effectiveness of the method I use simulated data. I create twelve scenarios based on the combinations of three outcome models (linear, logit and Poisson) and four types of multiplicative errors (non-systematic, systematic negative, systematic positive and heteroscedastic) affecting one of the explanatory variables. I show that SIMEX can be satisfactorily implemented in each of these scenarios. Furthermore, the method can also achieve partial adjustments even in scenarios where the actual distribution and prevalence of the measurement error differs substantially from what is assumed in the adjustment, which makes it an interesting sensitivity tool in those cases where all that is known about the error process is reduced to an educated guess.

Удосконалення структурних методів коригування адитивних похибок калібраторів напруги постійного струму

Удосконалення структурних методів коригування адитивних похибок калібраторів напруги постійного струму

Adjustment and Gross Errors Detection of Free Triangulation Geodetic Network Using Minimum-Norm Least-Squares Inverses and Data Snooping

We utilise minimum-norm least-squares based on the indirect observations methods to adjust our 2-dimensional triangulation network. The main objective of this paper is to optimally adjust the approximate coordinates of the nodes (points) of the given network. The network observations (11 measured distances and 17 angles) have been adjusted by being combined in linear system of equations in terms of free-network adjustment procedure to rigorously adjust the approximate coordinates over the network points. We obtained better converged values by applying an iterative procedure, the minimum corrections for the free-network coordinates are obtained after a number of five iterations. The data snooping procedure has been used to test the reliability and precision of the network observations. The T-Test criterion is then applied for gross error detection, five angles and two lines are suspected to include gross errors at a critical value of 1.98.

Modeling of Deuterium Ionization and Extraction From an Ion Source Driven by Heated Cathode

A new simple predictor–corrector method for stationary self-consistent electrostatic field modeling is developed on the basis of Comsol Multiphysics 3.5 capabilities. The method is implemented in the script written in Comsol Script 1.3. The basic idea of the method is iterative computation of space charge density from a set of virtually traced trajectories of charged particles. The script is tailored for modeling of charged particle movement in a cylindrically symmetric self-consistent stationary electric field of a gas-filled DD-neutron tube with an ion source driven by a heated cathode. The proposed approach is useful for determining the mode of operation of a tube (whether plasma is formed in ion source or the mode of operation is plasmaless) and for verification of design modifications for plasmaless neutron tubes. The computed charge fields are shown to be self-consistent with a space charge adjustment error of 2.5% at worst.

AJUSTES DE MODELOS VOLUMÉTRICOS PARA O CLONE Eucalyptus grandis x E. urophylla CULTIVADOS NO AGRESTE DE PERNAMBUCO

O presente trabalho teve como objetivo avaliar o ajuste de modelos volumétricos para um clone de Eucalyptus usando distribuição normal e t-Student, utilizando dados de um experimento implantado no Instituto Agronômico de Pernambuco (IPA) em São Bento do Una, PE. Para o ajuste dos modelos volumétricos de Silva e Bailey modificado, Chapman e Richard modificado, Schumacher e Hall e, Brody modificado, foram utilizados dados de 62 árvores cubadas rigorosamente pelo método de Smalian. Os critérios usados nas comparações das equações foi o valor ponderado (VP) entre o Índice de Ajuste corrigido (IAc) e o erro percentual absoluto médio (EPAM). De acordo com os resultados o modelo que mostrou melhores ajustes nas duas distribuições foi o de Schumacher e Hall, com melhores ajuste quando da distribuição t-Student. A distribuição t-Student promoveu melhorias nos ajustes das equações em relação à distribuição Normal, quando comparando as duas distribuições em cada equação.AbstractAdjustment of volumetric models for clone of Eucalyptus grandis x E. Urophylla grown on agreste, Pernambuco. This research aimed to evaluate the volumetric models fitting for Eucalyptus clone using normal and t-Student distributions, based on data from an experiment implanted at the Agronomic Institute of Pernambuco (IPA) in São Bento do Una, PE. In order to set the modified volumetric models of Silva and Bailey, modified Chapman and Richard, Schumacher and Hall, and modified Brody, we used data from 62 trees rigorously scaled by Smalian method. The criteria for equation comparing were the weighted value (PV) between the corrected index adjustment (IAc) and absolute mean error percentage (EPAM). According to the results, the model that best fits for the two distributions is Schumacher and Hall, with better adjustment related to the Student-t distribution. The t-Student distribution promoted improvements of equations regarding the Normal distribution, compared to the two distributions per equation.Keywords: Forest management; symmetric distributions; volume equations.

Impact of Uncertainties in Exposure Assessment on Thyroid Cancer Risk among Persons in Belarus Exposed as Children or Adolescents Due to the Chernobyl Accident.

BackgroundThe excess incidence of thyroid cancer in Ukraine and Belarus observed a few years after the Chernobyl accident is considered to be largely the result of 131I released from the reactor. Although the Belarus thyroid cancer prevalence data has been previously analyzed, no account was taken of dose measurement error.MethodsWe examined dose-response patterns in a thyroid screening prevalence cohort of 11,732 persons aged under 18 at the time of the accident, diagnosed during 1996–2004, who had direct thyroid 131I activity measurement, and were resident in the most radio-actively contaminated regions of Belarus. Three methods of dose-error correction (regression calibration, Monte Carlo maximum likelihood, Bayesian Markov Chain Monte Carlo) were applied.ResultsThere was a statistically significant (p<0.001) increasing dose-response for prevalent thyroid cancer, irrespective of regression-adjustment method used. Without adjustment for dose errors the excess odds ratio was 1.51 Gy− (95% CI 0.53, 3.86), which was reduced by 13% when regression-calibration adjustment was used, 1.31 Gy− (95% CI 0.47, 3.31). A Monte Carlo maximum likelihood method yielded an excess odds ratio of 1.48 Gy− (95% CI 0.53, 3.87), about 2% lower than the unadjusted analysis. The Bayesian method yielded a maximum posterior excess odds ratio of 1.16 Gy− (95% BCI 0.20, 4.32), 23% lower than the unadjusted analysis. There were borderline significant (p = 0.053–0.078) indications of downward curvature in the dose response, depending on the adjustment methods used. There were also borderline significant (p = 0.102) modifying effects of gender on the radiation dose trend, but no significant modifying effects of age at time of accident, or age at screening as modifiers of dose response (p>0.2).ConclusionsIn summary, the relatively small contribution of unshared classical dose error in the current study results in comparatively modest effects on the regression parameters.

ADJUSTMENT ERRORS IN ASCENDING AND DESCENDING PHASES OF TARGET LEVEL IN CONTROLLED FORCE EXERTION.

Hand grip force adjustment errors to ascending and descending phases of a sinusoidal target force in a controlled force exertion (CFE) test were measured and the laterality of responses evaluated. 75 men (M age = 19.6 yr., SD = 1.6) performed the CFE test after one practice trial by matching handgrip force to target level (5-25% of maximal grip force). The CFE errors in ascending and descending phases of the target force were calculated as the absolute differences between actual force and target force in each phase. There were significantly smaller CFE errors in the ascending phase for both dominant and non-dominant hands, but CFE error for the dominant hand was significantly smaller in both phases. Therefore, error in force exertion in the ascending and descending phases of the target force differed, and laterality influenced error in both phases.

Direct Torque Control for Permanent-Magnet Synchronous Machines Based on Duty Ratio Modulation

This paper proposes a novel duty ratio modulated direct torque control (DDTC) to concurrently reduce torque ripple and stator flux ripple that are typically associated with conventional direct torque control (DTC). Three different methods of duty ratio determination are presented to achieve various control objectives, namely DDTC-final, DDTC-mean and DDTC-rms. Additionally, adjustable error weight coefficients are introduced to balance the torque ripple reduction and stator flux ripple reduction. Experimental results are presented to validate the effectiveness of proposed DDTC. Furthermore, the comparative evaluation of proposed DDTC, conventional DDTC and DTC is conducted on the basis of several criteria to verify the superiority of proposed DDTC.

Allergy immunotherapy for allergic rhinitis effectively prevents asthma: Results from a large retrospective cohort study

Allergic rhinitis (AR) is a main risk factor for the development of asthma. Two randomized open-label trials indicated that allergy immunotherapy (AIT) prevents the onset of asthma in patients with AR. However, these trials have methodological limitations, and it is unclear to what extent this experimental efficacy translates into clinical effectiveness. We sought to investigate the effectiveness of AIT to prevent asthma in patients with AR. Using routine health care data from German National Health Insurance beneficiaries, we identified a consecutive cohort of 118,754 patients with AR but without asthma who had not received AIT in 2005. These patients were stratified into one group starting AIT in 2006 and one group receiving no AIT in 2006. Both groups were observed regarding the risk of incident asthma in 2007 to 2012. Risk ratios (RRs) were calculated with generalized linear models by using a Poisson link function with robust error variance and adjustment for age, sex, health care use because of AR, and use of antihistamines. In a total of 2431 (2.0%) patients, AIT was started in 2006. Asthma was newly diagnosed from 2007-2012 in 1646 (1.4%) patients. The risk of incident asthma was significantly lower in patients exposed to AIT (RR, 0.60; 95% CI, 0.42-0.84) compared with patients receiving no AIT in 2006. Sensitivity analyses suggested significant preventive effects of subcutaneous immunotherapy (RR, 0.54; 95% CI, 0.38-0.84) and AIT including native (nonallergoid) allergens (RR, 0.22; 95% CI, 0.02-0.68). AIT for 3 or more years tended to have stronger preventive effects than AIT for less than 3 years. AIT effectively prevents asthma in patients with AR in a real-world setting. Confounding by indication cannot be excluded but would lead to an underestimation of the true preventive effects of AIT.

Analysis of error-prone survival data under additive hazards models: measurement error effects and adjustments.

Covariate measurement error occurs commonly in survival analysis. Under the proportional hazards model, measurement error effects have been well studied, and various inference methods have been developed to correct for error effects under such a model. In contrast, error-contaminated survival data under the additive hazards model have received relatively less attention. In this paper, we investigate this problem by exploring measurement error effects on parameter estimation and the change of the hazard function. New insights of measurement error effects are revealed, as opposed to well-documented results for the Cox proportional hazards model. We propose a class of bias correction estimators that embraces certain existing estimators as special cases. In addition, we exploit the regression calibration method to reduce measurement error effects. Theoretical results for the developed methods are established, and numerical assessments are conducted to illustrate the finite sample performance of our methods.

Age differences in reactive strategies and execution time during choice stepping with visual interference.

We aimed to explore the effects of visual interference from a flanker task on a reactive strategy and execution speed of choice stepping among young and older adults. Twenty-two healthy young (21.9±1.4years) and 21 older participants (72.6±4.9years) were instructed to execute forward stepping as quickly and accurately as possible on the side indicated by a central arrow (←left vs. right→) of a visual cue during a neutral condition. During a flanker condition, participants were additionally required to ignore flanker arrows on each side of the central arrow (→→→→→ congruent or incongruent →→←→→). Errors in the direction of the initial weight transfer [anticipatory postural adjustment (APA) errors], step execution time, and divided phases (reaction, APA, and swing phases) were measured from the data of vertical force. Incongruence had larger effects on step execution times and APA phase in older adults than in young adults, while incongruence had smaller effects on reaction phase in older adults than in young adults. Step execution times were prolonged for trials with APA errors relative to trials without those in both groups. Only older adults showed that step execution times during trials with APA errors increased prominently in the incongruent condition as compared to the other conditions. Older adults might have a tendency to make hastier judgments, and might be vulnerable to potential motor program errors caused by an interference effect. Composite measurement of inhibition and stepping in a functional context may increase discriminative ability for age-related deficits in postural control.

Error adjustments for file linking methods using encrypted unique client identifier (eUCI) with application to recently released prisoners who are HIV+.

Incarceration provides an opportunity to test for HIV, provide treatment such as highly active anti-retroviral therapy, as well as link infected persons to comprehensive HIV care upon their release. A key factor in assessing the success of a program that links released individuals to care is the time from release to receiving care in the community (linkage time). To estimate the linkage time, records from correction systems are linked to Ryan White Clinic data using encrypted Unique Client Identifier (eUCI). Most of the records that were linked using eUCI belong to the same individual; however, in some cases, it may link records incorrectly, or not identify records that should have been linked. We propose a Bayesian procedure that relies on the relationships between variables that appear in either of the data sources, as well as variables that exists in both to identify correctly linked records among all linked records. The procedure generates K datasets in which each pair of linked records is identified as a true link or a false link. The K datasets are analyzed independently, and the results are combined using Rubin's multiple imputation rules. A small validation dataset is used to examine different statistical models and to inform the prior distributions of the parameters. In comparison with previously proposed methods, the proposed method utilizes all of the available data and is both flexible and computationally efficient. In addition, this approach can be applied in other file linking applications.

Sugar-sweetened beverage intake and cardiovascular risk factor profile in youth with type 1 diabetes: application of measurement error methodology in the SEARCH Nutrition Ancillary Study.

The SEARCH Nutrition Ancillary Study aims to investigate the role of dietary intake on the development of long-term complications of type 1 diabetes in youth, and capitalise on measurement error (ME) adjustment methodology. Using the National Cancer Institute (NCI) method for episodically consumed foods, we evaluated the relationship between sugar-sweetened beverage (SSB) intake and cardiovascular risk factor profile, with the application of ME adjustment methodology. The calibration sample included 166 youth with two FFQ and three 24 h dietary recall data within 1 month. The full sample included 2286 youth with type 1 diabetes. SSB intake was significantly associated with higher TAG, total and LDL-cholesterol concentrations, after adjusting for energy, age, diabetes duration, race/ethnicity, sex and education. The estimated effect size was larger (model coefficients increased approximately 3-fold) after the application of the NCI method than without adjustment for ME. Compared with individuals consuming one serving of SSB every 2 weeks, those who consumed one serving of SSB every 2 d had 3.7 mg/dl (0.04 mmol/l) higher TAG concentrations and 4.0 mg/dl (0.10 mmol/l) higher total cholesterol and LDL-cholesterol concentrations, after adjusting for ME and covariates. SSB intake was not associated with measures of adiposity and blood pressure. Our findings suggest that SSB intake is significantly related to increased lipid levels in youth with type 1 diabetes, and that estimates of the effect size of SSB on lipid levels are severely attenuated in the presence of ME. Future studies in youth with diabetes should consider a design that will allow for the adjustment for ME when studying the influence of diet on health status.

Rainfall estimation for real time flood monitoring using geostationary meteorological satellite data

Rainfall estimation by geostationary meteorological satellite data provides good spatial and temporal resolutions. This is advantageous for real time flood monitoring and warning systems. However, a rainfall estimation algorithm developed in one region needs to be adjusted for another climatic region. This work proposes computationally-efficient rainfall estimation algorithms based on an Infrared Threshold Rainfall (ITR) method calibrated with regional ground truth. Hourly rain gauge data collected from 70 stations around the Chao-Phraya river basin were used for calibration and validation of the algorithms. The algorithm inputs were derived from FY-2E satellite observations consisting of infrared and water vapor imagery. The results were compared with the Global Satellite Mapping of Precipitation (GSMaP) near real time product (GSMaP_NRT) using the probability of detection (POD), root mean square error (RMSE) and linear correlation coefficient (CC) as performance indices. Comparison with the GSMaP_NRT product for real time monitoring purpose shows that hourly rain estimates from the proposed algorithm with the error adjustment technique (ITR_EA) offers higher POD and approximately the same RMSE and CC with less data latency.

DEVELOPMENT OF INTEGRATION AND ADJUSTMENT METHOD FOR SEQUENTIAL RANGE IMAGES

Abstract. With increasing widespread use of three-dimensional data, the demand for simplified data acquisition is also increasing. The range camera, which is a simplified sensor, can acquire a dense-range image in a single shot; however, its measuring coverage is narrow and its measuring accuracy is limited. The former drawback had be overcome by registering sequential range images. This method, however, assumes that the point cloud is error-free. In this paper, we develop an integration method for sequential range images with error adjustment of the point cloud. The proposed method consists of ICP (Iterative Closest Point) algorithm and self-calibration bundle adjustment. The ICP algorithm is considered an initial specification for the bundle adjustment. By applying the bundle adjustment, coordinates of the point cloud are modified and the camera poses are updated. Through experimentation on real data, the efficiency of the proposed method has been confirmed.

Mathematical Model Regarding the Processing Accuracy in Milling of Spherical Surfaces

The paper presents a mathematical model that allows the determination of sphericity deviation for milling of kinematic generated spherical surfaces, considering the influence of the adjustment errors of the technological system over the processing accuracy. The model highlights the importance of diminishing the adjustment errors and the clearances in the technological system. Also, the mathematical model allows the selection of a processing technological system according to the desired accuracy for the manufactured spherical parts.

Chemotherapy e-prescribing: opportunities and challenges.

Chemotherapy drugs are characterized by low therapeutic indices and significant toxicities at clinically prescribed doses, raising serious issues of drug safety. The safety of the chemotherapy medication use process is further challenged by regimen complexity and need to tailor treatment to patient status. Errors that occur during chemotherapy prescribing are associated with serious and life-threatening outcomes. Computerized provider order entry (CPOE) systems were shown to reduce overall medication errors in ambulatory and inpatient settings. The adoption of chemotherapy CPOE is lagging due to financial cost and cultural and technological challenges. Institutions that adopted infusional or oral chemotherapy electronic prescribing modified existing CPOE systems to allow chemotherapy prescribing, implemented chemotherapy-specific CPOE systems, or developed home-grown chemotherapy electronic prescribing programs. Implementation of chemotherapy electronic prescribing was associated with a significant reduction in the risk of prescribing errors, most significantly dose calculation and adjustment errors. In certain cases, implementation of chemotherapy CPOE was shown to improve the chemotherapy use process. The implementation of chemotherapy CPOE may increase the risk of new types of errors, especially if processes are not redesigned and adapted to CPOE. Organizations aiming to implement chemotherapy CPOE should pursue a multidisciplinary approach engaging all stakeholders to guide system selection and implementation. Following implementation, organizations should develop and use a risk assessment process to identify and evaluate unanticipated consequences and CPOE-generated errors. The results of these analyses should serve to further enhance the chemotherapy electronic prescribing process and improve the quality and safety of cancer care.

Accessory stimulus modulates executive function during stepping task.

When multiple sensory modalities are simultaneously presented, reaction time can be reduced while interference enlarges. The purpose of this research was to examine the effects of task-irrelevant acoustic accessory stimuli simultaneously presented with visual imperative stimuli on executive function during stepping. Executive functions were assessed by analyzing temporal events and errors in the initial weight transfer of the postural responses prior to a step (anticipatory postural adjustment errors). Eleven healthy young adults stepped forward in response to a visual stimulus. We applied a choice reaction time task and the Simon task, which consisted of congruent and incongruent conditions. Accessory stimuli were randomly presented with the visual stimuli. Compared with trials without accessory stimuli, the anticipatory postural adjustment error rates were higher in trials with accessory stimuli in the incongruent condition and the reaction times were shorter in trials with accessory stimuli in all the task conditions. Analyses after division of trials according to whether anticipatory postural adjustment error occurred or not revealed that the reaction times of trials with anticipatory postural adjustment errors were reduced more than those of trials without anticipatory postural adjustment errors in the incongruent condition. These results suggest that accessory stimuli modulate the initial motor programming of stepping by lowering decision threshold and exclusively under spatial incompatibility facilitate automatic response activation. The present findings advance the knowledge of intersensory judgment processes during stepping and may aid in the development of intervention and evaluation tools for individuals at risk of falls.

Analysis of Choice Stepping with Visual Interference Can Detect Prolonged Postural Preparation in Older Adults with Mild Cognitive Impairment at High Risk of Falling

Background/Aims: We aimed to clarify postural control deficits in older adults with mild cognitive impairment (MCI) at high risk of falling by addressing the inhibitory process. Methods: This study involved 376 community-dwelling older adults with MCI. Participants were instructed to execute forward stepping on the side indicated by the central arrow while ignoring the 2 flanking arrows on each side (→→→→→, congruent, or →→←→→, incongruent). Initial weight transfer direction errors [anticipatory postural adjustment (APA) errors], step execution times, and divided phases (reaction, APA, and swing phases) were measured from vertical force data. Participants were categorized as fallers (n = 37) and non-fallers (n = 339) based on fall experiences in the last 12 months. Results: There were no differences in the step execution times, swing phases, step error rates, and APA error rates between groups, but fallers had a significantly longer APA phase relative to non-fallers in trials of the incongruent condition with APA errors (p = 0.005). Fallers also had a longer reaction phase in trials with the correct APA, regardless of the condition (p = 0.01). Conclusion: Analyses of choice stepping with visual interference can detect prolonged postural preparation as a specific falling-associated deficit in older adults with MCI.

New Method for Positional Cartographic Quality Control in Digital Mapping

AbstractQuality control applies to many attributes of a map: completeness, reliability, adherence to symbology specifications, interpretation errors, feature accuracy, and others. This article focuses on a map’s positional accuracy and presents a new method for cartographic quality control applied not just to a single chart, as is usual, but to digital mapping as a whole, generated by a photogrammetric process. The first step is to define the size of the sample using the estimated total number of possible control points in accordance with ISO 2859-1. The second step is to select a set of control points in homogeneous regions defined by a criterion that involves factors such as block adjustment errors, declivity, distance to control points, and operator skills. Then, these control points are surveyed both in a reference and more accurate source and in the cartographic base to be controlled, and the differences between the coordinates of the corresponding points are calculated. Finally, statistical tests ar...