Precision Goals Research Articles

Ep 15-A3 Precision-Based Verification of Original and Novel Commercial Kits of CRP on Beckman Coulter Au5800.

CRP is a hepatic acute-phase reactant protein, which is primarily induced by the interleukin-6 action due to an inflammatory/infectious process. Precision is closeness of agreement between indications or measured quantity values obtained by replicate measurements on the same or similar objects under specified conditions. Precision goals should be stated as the maximum allowable imprecision, SD, and/or CV expressed as a percentage (% CV) at each analyte´s concentration to be tested. The aim of this study was to verify the two different manufacturers' claims on C-reactive protein (CRP) based on the Clinical and Laboratory Standards Institute (CLSI) EP 15-A3 document. To represent low, intermediate, and high level, 3 sera pools were prepared from remnant sera of patients. After the familiarization period of the operator, two runs per day (morning and afternoon) with ten replicates per run were performed for five days for each measurand concentrations. Original CRP kit of Beckman uses latex immunoturbidimetric assay (OSR 6299, Beckman) and novel kit practices enzymatic immunoturbidimetric assay (B21220, Bioanalytic) were utilized to measure CRP. For both kits, only one calibration was applied before the study in favor of daily internal control results within the eligible area. The original kit failed at all levels, even if the upper verification limit was applied. Novel kit passed for the intermediate- and high-level claim of the manufacturers. The highest CV% was 5.24%, and the EFLM recommendation for CRP is 8.5% at the optimum level. Such experiments with expanded data should be performed with daily calibration to provide manufacturers' claim. Otherwise, it is hard to pass the precision verification. Studies are valuable in terms of demonstrating the reproducibility of the produced kits in end-user laboratories.

Determining biological variation of serum parathyroid hormone in healthy adults.

IntroductionMeasurement of parathyroid hormone (PTH) is essential in the investigation and management of calcium metabolism disorders. To assess the significance of any assay result when clinical decision making biological variation (BV) of the measurand must be taken into consideration. The aim of the present study is determining the BV parameters for serum PTH.Materials and methodsBlood samples were taken at weekly intervals from 20 healthy subjects for ten weeks in this prospective BV study. Serum “intact PTH” concentrations were measured with electrochemiluminescence method. Biological variation parameters were estimated using the approach proposed by Fraser.ResultsThe values of within-subject biological variation (CVI), between-subject biological variation (CVG), analytical variation (CVA), reference change value (RCV) and individuality index (II) for serum PTH were 21.1%, 24.9%, 3.8%, 59.4% and 0.8%, respectively. Within-subject biological variation and CVG were also determined according to gender separately; 18.5% and 24.0%; 26.2% and 18.6% for male and female, respectively. Calculated desirable precision and bias goals were < 10.6% and < 6.3%, respectively.ConclusionThis study may contribute to BV data on serum PTH as it includes a sufficient number of volunteers from both genders over an acceptable period of time. We do not recommend the usage of population-based reference intervals for serum PTH concentrations. Reference change value may be helpful for the evaluation of serial serum PTH results. Nonetheless, evaluation of data according to gender is necessary when setting analytical performance specifications.

Double sampling for post-stratification in forest inventory

Many national forest inventories (NFI) use auxiliary data to increase the precision of estimates. Typically, this is accomplished via stratified estimation techniques that rely on assignment of similar sample plot observations to strata constructed with the goal of lowering the variance of estimates. While early applications of stratification used strata constructed from photo-interpretation of aerial photography, current technology makes using wall-to-wall digital map information more appealing due to automated processing capabilities; however, there is generally a reduction in classification accuracy in comparison with photo-interpretation and a concomitant decrease in the precision of estimates. While most established NFI have permanent plots and employ post-stratification (PS) with stratum weights known from a map, it is unclear what are the compromises compared to using a photo-interpretation (PI) approach. In this study, differences in cost and precision were evaluated for post-stratification using strata derived from a digital map and double sampling for post-stratification (DSPS) with strata created from PI of aerial imagery. It was found that DSPS consistently provided better precision than PS for estimates of total biomass and forestland area with approximately 13 PI points per sample plot, which incurred a cost increase equivalent to 0.5% per ground plot. Increasing the number of PI points per plot resulted in further gains in precision, with cost increases proportional to the PI intensity. To attain specific precision goals, DSPS was generally less costly than increasing the sample size under PS, although the PS design was more cost-effective if the PI intensity was too low. The results of this study provide a decision framework for inventory planners considering sampling designs that rely on post-stratified estimation.

Searchable encryption approaches: attacks and challenges

Searchable encryption (SE) is a cryptographic technique that allows the users to perform search over outsourced encrypted data in cloud servers while preserving the privacy of data and search query. In order to preserve privacy and security, data owners use various encryption schemes to encrypt their data and indexes. Due to the vulnerabilities in the encryption schemes adopted by SE schemes, information leakages are possible from the encrypted data. The cloud servers use various information disclosure attacks that exploit these leakages to infer plaintext information. In this paper, we analyze the existing SE approaches with respect to their security and precision goals and possible attacks on them. We also identify the root causes of these attacks and their remedies. An experimental study is also performed to investigate the susceptibility of SE schemes against attacks and countermeasures to prevent them.

Guidance for quality control practices and precision goals for CBCs based on IQMH patterns-of-practice survey.

Effective medical laboratory quality management systems ensure confidence in analyzing and reporting accurate and reliable patient results. To guarantee quality assurance, each laboratory needs appropriate internal quality control (IQC) procedures to monitor their test systems. The Institute for Quality Management in Healthcare (IQMH) Centre for Proficiency Testing conducted a survey on quality control (QC) practices in routine hematology. An online survey was sent to 184 Ontario laboratories performing complete blood counts (CBC) and leukocyte differentials. All participants used three levels of commercial QC for test system monitoring. Eighty percent of laboratories supplement with in-house patient QC. The frequency of QC analysis was variable based on: Manufacturer recommendations (80%) Parameter stability (25%) Clinical impact of incorrect results (21%) Number of samples potentially requiring retesting if there is a QC failure (11%). All laboratories used established QC rules and limits to monitor results. They utilized various methods in establishing limits including: Standard deviation of QC results (60%) Manufacturer precision goals (55%) Published precision goals (24%) IQMH allowable performance limits (APLs) (37%). Considerable variation in QC practices of Ontario laboratories was identified, and consensus practice recommendations and precision goals were developed to guide and standardize QC practice.

Creatinine Assay Attainment of Analytical Performance Goals Following Implementation of IDMS Standardization: Further Improvements Required.

Background:The international initiative to standardize creatinine (Cr) assays by tracing reference materials to Isotope Dilution Mass Spectrometry (IDMS) assigned values was implemented to reduce interlaboratory variability and improve assay accuracy.Objective:The aims of this study were to examine whether IDMS standardization has improved Cr assay accuracy (bias), interlaboratory variability (precision), total error (TE), and attainment of recommended analytical performance goals.Methods:External Quality Assessment (EQA) data (n = 66 challenge vials) from Ontario, Canada, were analyzed. The bias, precision, TE, and the number of EQA challenge vials meeting performance goals were determined by assay manufacturer before (n = 32) and after (n = 34) IDMS implementation.Results:The challenge vials with the worst bias and precision were spiked with known common interfering substances (glucose and bilirubin). IDMS standardization improved assay bias (10.4%-1.6%, P < .001), but precision remained unchanged (5.0%-4.7%, P = .5) with performance goals not consistently being met. Precision and TE goals based on biologic variation were attained by only 29% to 69% and 32% to 62% of challenge vials.Conclusions:While IDMS standardization has improved Cr assay accuracy and thus reduced TE, significant interlaboratory variability remains. Contemporary Cr assays do not currently meet the standards required to allow for accurate and consistent estimated glomerular filtration rate assessment and chronic kidney disease diagnosis across laboratories. Further improvements in Cr assay performance are needed.

Point of Care Testing for HbA1c in Primary Care—cobas b 101 Instrument Evaluation

Objective This study aims to evaluate the suitability of the cobas b 101 instrument for the measurement of HbA1c in primary care. Methods Ten primary health care centres were involved in the evaluation of the cobas b 101 instrument. Inter-assay imprecision was assessed through quality control testing by practice nurses in the primary health care centers. Intra-assay imprecision was assessed through quality control testing by scientific staff in a laboratory setting. Accuracy was assessed through 15 patient comparison samples at each site, with samples tested on the b 101 instrument and sent to the local laboratory for analysis. Surveys were conducted assessing user satisfaction. Results All imprecision results met the minimum and desirable precision goals. Overall patient comparison results demonstrated good correlation (r ≥ 0.97). An overall instrument bias of 6.5% was seen. All laboratory-diagnosed diabetic patients were classified as diabetic on the b 101 instrument. User satisfaction results were high, recognizing confidence in the b 101 results and advantages to laboratory testing. Conclusions This study demonstrates that HbA1c testing in primary care through the cobas b 101 instrument is a suitable alternative to laboratory methods, with good precision, correlation, and user satisfaction results.

Impact of low-energy nuclear excitations on neutrino-nucleus scattering at MiniBooNE and T2K kinematics

[Background] Meticulous modeling of neutrino-nucleus interactions is essential to achieve the unprecedented precision goals of present and future accelerator-based neutrino-oscillation experiments. [Purpose] Confront our calculations of charged-current quasielastic cross section with the measurements of MiniBooNE and T2K, and to quantitatively investigate the role of nuclear-structure effects, in particular, low-energy nuclear excitations in forward muon scattering. [Method] The model takes the mean-field (MF) approach as the starting point, and solves Hartree-Fock (HF) equations using a Skyrme (SkE2) nucleon-nucleon interaction. Long-range nuclear correlations are taken into account by means of the continuum random-phase approximation (CRPA) framework. [Results] We present our calculations on flux-folded double differential, and flux-unfolded total cross sections off $^{12}$C and compare them with MiniBooNE and (off-axis) T2K measurements. We discuss the importance of low-energy nuclear excitations for the forward bins. [Conclusions] The CRPA predictions describe the gross features of the measured cross sections. They underpredict the data (more in the neutrino than in the antineutrino case) because of the absence of processes beyond pure quasielastic scattering in our model. At very forward muon scattering, low-energy nuclear excitations ($\omega < $ 50 MeV) account for nearly 50% of the flux-folded cross section.

Neutrino-nucleus interactions in the few-GeV region

Knowledge of neutrino interaction cross sections is an important and necessary ingredient in any neutrino measurement and it is crucial to achieve the precision goals of the neutrino oscillation program, making possible new discoveries like the CP violation in the leptonic sector. We briefly review the major features of the neutrino cross sections in the few-GeV region, paying special attention to nuclear effects.

Useful measures and models for analytical quality management in medical laboratories.

The 2014 Milan Conference "Defining analytical performance goals 15 years after the Stockholm Conference" initiated a new discussion of issues concerning goals for precision, trueness or bias, total analytical error (TAE), and measurement uncertainty (MU). Goal-setting models are critical for analytical quality management, along with error models, quality-assessment models, quality-planning models, as well as comprehensive models for quality management systems. There are also critical underlying issues, such as an emphasis on MU to the possible exclusion of TAE and a corresponding preference for separate precision and bias goals instead of a combined total error goal. This opinion recommends careful consideration of the differences in the concepts of accuracy and traceability and the appropriateness of different measures, particularly TAE as a measure of accuracy and MU as a measure of traceability. TAE is essential to manage quality within a medical laboratory and MU and trueness are essential to achieve comparability of results across laboratories. With this perspective, laboratory scientists can better understand the many measures and models needed for analytical quality management and assess their usefulness for practical applications in medical laboratories.

Designing and Interpreting Limiting Dilution Assays: General Principles and Applications to the Latent Reservoir for Human Immunodeficiency Virus-1.

Limiting dilution assays are widely used in infectious disease research. These assays are crucial for current human immunodeficiency virus (HIV)-1 cure research in particular. In this study, we offer new tools to help investigators design and analyze dilution assays based on their specific research needs. Limiting dilution assays are commonly used to measure the extent of infection, and in the context of HIV they represent an essential tool for studying latency and potential curative strategies. Yet standard assay designs may not discern whether an intervention reduces an already miniscule latent infection. This review addresses challenges arising in this setting and in the general use of dilution assays. We illustrate the major statistical method for estimating frequency of infectious units from assay results, and we offer an online tool for computing this estimate. We recommend a procedure for customizing assay design to achieve desired sensitivity and precision goals, subject to experimental constraints. We consider experiments in which no viral outgrowth is observed and explain how using alternatives to viral outgrowth may make measurement of HIV latency more efficient. Finally, we discuss how biological complications, such as probabilistic growth of small infections, alter interpretations of experimental results.

Internal Quality Control Practices in Coagulation Laboratories: recommendations based on a patterns-of-practice survey.

Internal quality control (IQC) procedures are crucial for ensuring accurate patient test results. The IQMH Centre for Proficiency Testing conducted a web-based survey to gather information on the current IQC practices in coagulation testing. A questionnaire was distributed to 174 Ontario laboratories licensed to perform prothrombin time (PT) and activated partial thromboplastin time (APTT). All laboratories reported using two levels of commercial QC (CQC); 12% incorporate pooled patient plasma into their IQC program; >68% run CQC at the beginning of each shift; 56% following maintenance, with reagent changes, during a shift, or with every repeat sample; 6% only run CQC at the beginning of the day and 25% when the instruments have been idle for a defined period of time. IQC run frequency was determined by manufacturer recommendations (71%) but also influenced by the stability of test (27%), clinical impact of an incorrect test result (25%), and sample's batch number (10%). IQC was monitored using preset limits based on standard deviation (66%), precision goals (46%), or allowable performance limits (36%). 95% use multirules. Failure actions include repeating the IQC (90%) and reporting patient results; if repeat passes, 42% perform repeat analysis of all patient samples from last acceptable IQC. Variability exists in coagulation IQC practices among Ontario clinical laboratories. The recommendations presented here would be useful in encouraging standardized IQC practices.

Estimates of Intraclass Correlation Coefficients From Longitudinal Group-Randomized Trials of Adolescent HIV/STI/Pregnancy Prevention Programs.

Group-randomized trials (GRTs) are one of the most rigorous methods for evaluating the effectiveness of group-based health risk prevention programs. Efficiently designing GRTs with a sample size that is sufficient for meeting the trial's power and precision goals while not wasting resources exceeding them requires estimates of the intraclass correlation coefficient (ICC)-the degree to which outcomes of individuals clustered within groups (e.g., schools) are correlated. ICC estimates vary widely depending on outcome, population, and setting, and small changes in ICCs can have large effects on the sample size needed to estimate intervention effects. This study addresses a gap in the literature by providing estimates of ICCs for adolescent sexual risk-taking outcomes under a range of study conditions. Multilevel regression analyses were applied to existing data from four federally funded GRTs of school-based HIV/STI/pregnancy prevention programs to obtain a variety of ICC estimates. ICCs ranged from 0 to 0.15, with adjustment for covariates and repeated measurements reducing the ICC in the majority of cases. Minimum detectable effect sizes with 80% power and 0.05 significance levels ranged from small to medium Cohen's d (0.13 to 0.53) assuming 20 schools of 100 students each. This study provides the first known set of ICC estimates for investigators to use when planning studies of school-based programs to prevent sexual risk behaviors in youth. The results provide further evidence of the importance of using the appropriate adjusted ICC estimate at the design stage to maximize resources in costly GRTs.

Progress and open questions in the physics of neutrino cross sections at intermediate energies

New and more precise measurements of neutrino cross sections have renewed interest in a better understanding of electroweak interactions on nucleons and nuclei. This effort is crucial to achieving the precision goals of the neutrino oscillation program, making new discoveries, like the CP violation in the leptonic sector, possible. We review the recent progress in the physics of neutrino cross sections, putting emphasis on the open questions that arise in the comparison with new experimental data. Following an overview of recent neutrino experiments and future plans, we present some details about the theoretical development in the description of (anti)neutrino-induced quasielastic (QE) scattering and the role of multi-nucleon QE-like mechanisms. We cover not only pion production in nucleons and nuclei but also other inelastic channels including strangeness production and photon emission. Coherent reaction channels on nuclear targets are also discussed. Finally, we briefly describe some of the Monte Carlo event generators, which are at the core of all neutrino oscillation and cross-section measurements.

An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

Abstract. Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42−, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack. Using this and results from a previous study, it is concluded that if the MUs and the filter pack were sampling the same particle size, the MUs would have good agreement in terms of precision and accuracy. The MARGA performed moderately well in measuring HNO3 and NH3, though neither met the linear regression slope goals. However, recommendations for improving the measurement of HNO3 and NH3 are discussed. It is concluded that SO42-, SO2, NO3-, HNO3, NH4+, and NH3 concentrations can be measured with acceptable accuracy and precision when the MARGA is operated in conjunction with the recommendations outlined in the manuscript.

Quadratic electroweak corrections for polarized Møller scattering

This paper discusses the two-loop electroweak radiative corrections to the parity-violating ${e}^{\ensuremath{-}}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}{e}^{\ensuremath{-}}(\ensuremath{\gamma})(\ensuremath{\gamma}\ensuremath{\gamma})$ scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at future high-energy colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments.

A Novel Multi-Classifier Layered Approach to Improve Minority Attack Detection in IDS

Due to the tremendous growth of network based services, intrusion detection has emerged as an important technique for network security. While variety of security techniques are being developed and a lot of research is going on intrusion detection, but the field lacks an integrated approach with high detection rate (recall) and precision for minority attacks namely R2L and U2R. However, the recall and precision goals are often conflicting and attacking them simultaneously may not work well, especially when some of the classes are rare. This paper presents a novel layered approach with multi-classifier by combining naïve bayes classifier (NBC) and naive bayes tree (NBTree) to improve detection rate and precision of minority class without hurting the performance of majority class. We identify important reduced feature set for each attack separately, to form layered approach. The proposed approach scales up the recall and precision for major as well as minor attacks, and keeps the false positives at acceptable level in intrusion detection.

Spectroscopy of dipolar fermions in layered two-dimensional and three-dimensional lattices

Motivated by ongoing measurements at JILA, we calculate the recoil-free spectra of dipolar interacting fermions, for example ultracold heteronuclear molecules, in a one-dimensional lattice of two-dimensional layers or ``pancakes,'' spectroscopically probing transitions between different internal (e.g., rotational) states. We additionally incorporate $p$-wave interactions and losses, which are important for reactive molecules such as KRb. Moreover, we consider other sources of spectral broadening: interaction-induced quasiparticle lifetimes and the different polarizabilities of the rotational states used for the spectroscopy. Although our main focus is molecules, some of the calculations are also useful for optical lattice atomic clocks. For example, understanding the $p$-wave shifts between identical fermions and small dipolar interactions coming from the excited clock state is necessary to reach future precision goals. Finally, we consider the spectra in a deep three-dimensional lattice and show how they give a great deal of information about static correlation functions, including all the moments of the density correlations between nearby sites. The range of correlations measurable depends on spectroscopic resolution and the dipole moment.

A Bayesian hierarchical occupancy model for track surveys conducted in a series of linear, spatially correlated, sites

Summary1. Natural resource agencies often rely on surveys of animal sign (e.g. scat, scent marks, tracks) for population assessment, with repeat surveys required to model and account for uncertain detection. Using river otter Lontra canadensis snow‐track survey data as a motivating example, we develop a 3‐level occupancy model with parameters that describe (i) site‐level occupancy probabilities, (ii) otter movement (and thus, track availability) and (iii) recorded presence–absence of tracks (conditional on the availability of tracks for detection).2. We incorporated several recent developments in occupancy modelling, including the presence of both false negatives and false positives, spatial and temporal correlation and repeated sampling across distinct observers.3. We investigated optimal allocation of sampling effort (e.g. within and among snowfall events) using simulations. We also compared models that allowed site‐level occupancy and track‐laying processes to be spatially correlated with models that assumed independence among sites.4. Both types of models (independence and spatial) performed well across a range of simulated parameter values, but the spatial model resulted in more accurate point estimates for detection parameters and credibility intervals with better coverage rates when data were spatially correlated. When applied to real data, the spatial model resulted in a higher estimate of the occupancy rate than the baseline model (0·82 vs. 0·59). A minimum of 15–20 helicopter flights, distributed among at least three unique snow events, were needed to meet precision goals (standard error ).5. Synthesis and applications. We describe a flexible and robust occupancy modelling framework that accounts for heterogeneous detection rates in surveys of animal sign. The method allows for spatially correlated sites and should have broad relevance to surveys conducted by many natural resource agencies.

The European Pulsar Timing Array: current efforts and a LEAP toward the future

The European Pulsar Timing Array (EPTA) is a multi-institutional, multi-telescope collaboration, with the goal of using high-precision pulsar timing to directly detect gravitational waves. In this paper we discuss the EPTA member telescopes, current achieved timing precision and near-future goals. We report a preliminary upper limit to the amplitude of a gravitational wave background. We also discuss the Large European Array for Pulsars, in which the five major European telescopes involved in pulsar timing will be combined to provide a coherent array that will give similar sensitivity to the Arecibo radio telescope, and larger sky coverage.