[Influence of municipal registry errors on the identification of a sample].
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Registries↗
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Results for “Sampling Errors”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
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Evaluation of a total hematology analysis system (Sysmex HS-430). Benefits for large laboratories by reducing manual work load and optimizing screening efficacy for pathologic samples.
In this study, the authors evaluated a closed tube total hematology analysis system, Sysmex HS-430 (HS), which consists of two automated hematology analyzers, Sysmex NE-8000, the reticulocyte analyzer, Sysmex R-3000, and a slide preparation unit integrated in an automated sample transport system (TOA Medical Electronics, Kobe, Japan). The suitability of the system was compared with a conventional hematology system (CS) consisting of two single standing Coulter STKS analyzers (Hialeah, FL), one automated reticulocyte counter Sysmex R-1000, and the manual blood smear preparation. Evaluation was performed following the concept suggested by the Austrian-German societies for Clinical Chemistry and Laboratory Medicine that includes the evaluation of personnel supply. Eight consecutive series with a total of 4,896 samples were analyzed on both systems. Evaluation revealed that the analysis time per series was 238 minutes on the HS-430 and 359 minutes on the CS. The mean analyzer down times because of technical reasons were 36 minutes on the HS and 32 minutes on the CS. The down time because of "nontechnical" reasons was 31 minutes on the HS-430, but 173 minutes on the CS, which was mainly because of discontinuous sample loading of analyzers of the CS. The average direct technical time effort for complete blood cell count (CBC) analyses, reticulocyte counts, and blood smear preparations per series was 23 minutes on the HS and 245 minutes on the CS. In summary, these data show that an automated system like the HS-430 saves 222 minutes of manual activities arising in a large routine hematology laboratory with a mean throughout of 612 samples per day. Furthermore, the system improves intralaboratory turnaround times, avoids human errors by automated sample identification, and guarantees more safety for laboratory staff by minimizing the contact with potential biohazards.
Blood Cell Count↗
Site-specific integrated pest management for high value crops: sample units for map generation using the Colorado potato beetle (Coleoptera: Chrysomelidae) as a model system.
Site-specific agriculture uses maps to optimize within-field placement of agricultural practices. This technology introduces the potential to optimize pest management by varying pesticide or other inputs to better match within-field variation in pest density. Current sampling plans are designed to estimate mean density and may not be suitable for mapping, although useful sampling plans could be developed for map generation for integrated pest management. Using Colorado potato beetle, Leptinotarsa decemlineata (Say), adults, larvae, and egg masses as model systems, the influence of the sample unit on map validity was explored. Adapting currently used sampling plans for potato integrated pest management by spatially referencing each sampled stem failed to resolve spatial dependence and resulted in maps with poor reliability. Increasing the sample unit improved resolution of spatial dependence and map reliability for each life stage. A distance-walk sample unit for adult and late instar Colorado potato beetles which has high potential for map generation is introduced. Using this sample unit, generalizations about Colorado potato beetle spatial dependence are made to discuss issues of developing sampling programs for map generation. An iterative process of sampling, spatial analysis, and error analysis is suggested for evaluating sample units for mapping pest density in high value crops.
Animals↗
The oxygenator arterial sampling port: a potential source of error.
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Blood Gas Analysis↗
A new colorimetric method for the measurement of serum calcium using a zinc-zincon indicator.
A new method is described for the measurement of serum calcium. Calcium in the sample displaces zinc from an EGTA complex, the zinc then forming a blue-coloured complex with a zincon indicator. The method is rapid, sensitive and linear; it may be applied directly to serum and is readily automated. No compound tested gave rise to any interference at physiological concentration, although excessive haemolysis leads to low results being obtained. To avoid interference from endogenous zinc a serum blank is required for each sample; this also avoids errors introduced by turbidity of the sample. The results obtained correlate well with atomic absorption spectroscopy (r = 0.935, y = 1.12x-0.28, n = 68).
Azo Compounds↗
The lack of effect of variable blood withdrawal rates on the measurement of mixed venous oxygen saturation.
In a study of 12 critically ill patients, values for mixed venous oxygen saturation (SVO2) were measured from samples of pulmonary arterial blood drawn at five rates of withdrawal (1, 3, 10, 20, and 30 ml/min). Samples were drawn from properly placed pulmonary arterial catheters with the balloon deflated. Physiologic stability was documented at the beginning and end of the sampling period in all but one patient. Results in each patient demonstrated a close grouping of values for SVO2 obtained at the five rates of withdrawal (largest standard deviation, 1.9 percent). Evaluations by paired t-test comparing all rates of withdrawal with the slowest rate (1 ml/min) showed no significant differences. The rate of withdrawal of the sample is not associated with significant errors in SVO2 when samples are drawn from a properly positioned pulmonary arterial catheter.
Adult↗
Refractive error and preferential looking visual acuity in human infants: a pilot study.
A clinical pilot study comparing refractive error and preferential looking (PL) visual acuity in infants 2 to 12 months of age is described. The PL visual acuity of 30 normal infants without significant visual disorders was assessed using the Acuity Card Procedure. Near retinoscopy was used to determine refractive error. Infants of this sample had monocular PL visual acuities similar to those established by McDonald et al. in a laboratory setting. Statistical analysis of the data for this sample of infants showed that refractive error did not change systematically from 2 to 12 months of age. We have found that results obtained with the Acuity Card Procedure in a clinical setting agree with infant visual acuity as described in the research literature. Refractive error did not correlate with changes in PL visual acuity in infants 2 to 12 months of age.
Humans↗
[Wrong collecting and sending of saliva samples as a source of expert error].
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Antigens↗
Direct monitoring system of analytical errors--combination analysis of kinetically different samples (author's transl).
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L-Lactate Dehydrogenase↗
Efficient DNA database laboratory strategy for high through-put STR typing of reference samples.
DNA intelligence databases were installed successfully in various countries during the past few years. It is a general trend that laboratories performing STR analysis for DNA databases have to adjust to increased sample through-put, especially when dealing with a high number of reference samples. In contrast to routine forensic casework analysis, where samples of suspects and unknown samples are interpreted with regard to the specific circumstances of the case and are kept distinctly apart from other cases, DNA databases consist of single, primarily unlinked DNA profiles. Problems areas associated with the high number of anonymous DNA profiles are the risk of logistic errors, such as sample mix-up during the laboratory procedure, and the risk of typing errors during manual transcription of data and/or results. Thus, DNA databases clearly require new laboratory strategies to rise to the challenge. This paper presents an efficient automated laboratory strategy on the platform of a laboratory management information system (LIMS) with the Austrian DNA Intelligence Database as example. Two goals were tackled in particular: first, data safety by avoiding both manual interaction during critical laboratory steps (i.e. when DNA is transferred form one tube into another), and errors due to manual transcription of sample information and results. Secondly, efficient sample processing by automizing the laboratory procedure with the help of robotic instruments, thus, giving the DNA staff more time to analyze data.
Austria↗
Color demosaicking via directional linear minimum mean square-error estimation.
Digital cameras sample scenes using a color filter array of mosaic pattern (e.g., the Bayer pattern). The demosaicking of the color samples is critical to the image quality. This paper presents a new color demosaicking technique of optimal directional filtering of the green-red and green-blue difference signals. Under the assumption that the primary difference signals (PDS) between the green and red/blue channels are low pass, the missing green samples are adaptively estimated in both horizontal and vertical directions by the linear minimum mean square-error estimation (LMMSE) technique. These directional estimates are then optimally fused to further improve the green estimates. Finally, guided by the demosaicked full-resolution green channel, the other two color channels are reconstructed from the LMMSE filtered and fused PDS. The experimental results show that the presented color demosaicking technique outperforms the existing methods both in PSNR measure and visual perception.
Algorithms↗
Response and nonresponse bias in oral health surveys.
Oral health surveys are undertaken to provide estimates of the dental health and behaviors of populations or population subgroups. However, the integrity of the data from sample surveys may be compromised by one or more sources of sampling and nonsampling error. An important source of nonsampling error is the failure to collect data from some of the individuals comprising the sample. Consequently, the response to a sample survey, and the direction and magnitude of bias induced by nonresponse, need to be taken into account when using estimates derived from sample surveys. Although the response rate to a survey is usually used as an indicator of the quality of the data it provides, nonresponse error is a function of nonresponse and the extent of differences in the characteristics of responders and nonresponders. Nonresponse may be managed in two ways. The first is to reduce nonresponse to a minimum using response-enhancement strategies. The second is the post-survey adjustment of data using weighting or imputation techniques to produce estimates that correct for nonresponse. This paper discusses issues concerning response and nonresponse bias in oral health surveys and provides guidelines on the management and reporting of nonresponse. It describes response-enhancement strategies to reduce noncontacts and refusals, sources of data to facilitate the comparison of responders and nonresponders, methods of assessing the degree of bias induced by nonresponse, techniques for producing adjusted survey estimates, and the assumptions on which these procedures and processes are based.
Bias↗
Statistical confidence for likelihood-based paternity inference in natural populations.
Paternity inference using highly polymorphic codominant markers is becoming common in the study of natural populations. However, multiple males are often found to be genetically compatible with each offspring tested, even when the probability of excluding an unrelated male is high. While various methods exist for evaluating the likelihood of paternity of each nonexcluded male, interpreting these likelihoods has hitherto been difficult, and no method takes account of the incomplete sampling and error-prone genetic data typical of large-scale studies of natural systems. We derive likelihood ratios for paternity inference with codominant markers taking account of typing error, and define a statistic delta for resolving paternity. Using allele frequencies from the study population in question, a simulation program generates criteria for delta that permit assignment of paternity to the most likely male with a known level of statistical confidence. The simulation takes account of the number of candidate males, the proportion of males that are sampled and gaps and errors in genetic data. We explore the potentially confounding effect of relatives and show that the method is robust to their presence under commonly encountered conditions. The method is demonstrated using genetic data from the intensively studied red deer (Cervus elaphus) population on the island of Rum, Scotland. The Windows-based computer program, CERVUS, described in this study is available from the authors. CERVUS can be used to calculate allele frequencies, run simulations and perform parentage analysis using data from all types of codominant markers.
Animals↗
Natural sample spaces and uncertain belief.
This article proposes a novel framework for understanding judgments of probability. Both accurate and inaccurate judgments are conceptualized in terms of the sets of information, or sample spaces, on which they are based. When appropriate sample spaces are easily accessed from memory (e.g., when they correspond to natural cognitive categories), people will make relatively accurate judgments; otherwise, people may substitute more accessible but inappropriate sample spaces and make judgment errors. In 3 experiments, the sample space framework was applied to account for the base rate fallacy. Results showed that (a) people spontaneously access sample spaces that correspond to natural categories, (b) reliance on inappropriate sample spaces produces the base rate fallacy, and (c) highlighting appropriate sample spaces improves the sensitivity of people's judgments to base rates. Discussion extends the framework to explain accuracy and error in other judgment domains.
Adult↗
Comparison of a two-stage and three-stage interim-analysis procedure.
A statistical model for combining p values from multiple tests of significance is used to define rejection and acceptance regions for two-stage and three-stage sampling plans. Type I error rates, power, frequencies of early termination decisions, and expected sample sizes are compared. Both the two-stage and three-stage procedures provide appropriate protection against Type I errors. The two-stage sampling plan with its single interim analysis entails minimal loss in power and provides substantial reduction in expected sample size as compared with a conventional single end-of-study test of significance for which power is in the adequate range. The three-stage sampling plan with its two interim analyses introduces somewhat greater reduction in power, but it compensates with greater reduction in expected sample size. Either interim-analysis strategy is more efficient than a single end-of-study analysis in terms of power per unit of sample size.
Bias↗
Stopping boundaries adjusted for sample size reestimation and negative stop.
We propose an approach to specify group sequential stopping boundaries adjusted for sample size reestimation and negative stop in interim analyses of a clinical trial. Sample size can be adjusted based on the observed delta at each interim to maintain the targeted power. The calculation of stopping boundaries incorporates possible changes in the type-I error due to sample size reestimation and/or negative stops; hence the overall type-I error is well controlled. This approach combines the advantages of the group sequential and sample size reestimation methods and is more efficient than either one alone. It provides flexibility in clinical trials and still maintains the integrity of these trials. When no early stop is planned, the stopping boundaries will be adjusted only for sample size reestimation. All calculations are given in closed mathematical forms and adjustments in stopping boundaries are based on the exact type-I error change. Therefore, the penalty for the type-I error inflation due to such interim conductions is kept to a minimum.
Algorithms↗
Optimal sampling time selection for parameter estimation in dynamic pathway modeling.
Systems Biology is an emerging research area, which considers mathematical representations of inter- and intra-cellular dynamics. Among the many research problems that have been addressed, dynamic modeling of signal transduction pathways has received increasing attention. The usual approach to represent intra-cellular dynamics are nonlinear, usually ordinary, differential equations. The purpose of the models is to test and generate hypothesis of specific pathways and it is therefore required to estimate model parameters from experimental data. The experiments to generate data are complex and expensive, as a consequence of which the time series available are usually rather short, with few if any replicates. Almost certainly, not all variables one would like to include in a model can be measured. Parameter estimation is therefore an important research problem in Systems Biology and the focus of this paper. In particular, we are interested in optimizing the sampling time selection in order to minimize the variance of the parameter estimation error. With few sampling time points feasible, their selection is of practical importance in experimental design. Finally, the theoretical results are supported with an application.
Computer Simulation↗
Evaluation of visible and near-infrared spectroscopy as a tool for assessing fiber fineness during mechanical preparation of dew-retted flax.
Flax fiber must be mechanically prepared to improve fineness and homogeneity of the sliver before chemical processing and wet-spinning. The changes in fiber characteristics are monitored by an airflow method, which is labor intensive and requires 90 minutes to process one sample. This investigation was carried out to develop robust visible and near-infrared calibrations that can be used as a rapid tool for quality assessment of input fibers and changes in fineness at the doubling (blending), first, second, third, and fourth drawing frames, and at the roving stage. The partial least squares (PLS) and principal component regression (PCR) methods were employed to generate models from different segments of the spectra (400-1100, 1100-1700, 1100-2498, 1700-2498, and 400-2498 nm) and a calibration set consisting of 462 samples obtained from the six processing stages. The calibrations were successfully validated with an independent set of 97 samples, and standard errors of prediction of 2.32 and 2.62 dtex were achieved with the best PLS (400-2498 nm) and PCR (1100-2498 nm) models, respectively. An optimized PLS model of the visible-near-infrared (vis-NIR) spectra explained 97% of the variation (R(2) = 0.97) in the sample set with a standard error of calibration (SEC) of 2.45 dtex and a standard error of cross-validation (SECV) of 2.51 dtex R(2) = 0.96). The mean error of the reference airflow method was 1.56 dtex, which is more accurate than the NIR calibration. The improvement in fiber fineness of the validation set obtained from the six production lines was predicted with an error range of -6.47 to +7.19 dtex for input fibers, -1.44 to +5.77 dtex for blended fibers at the doubling, and -4.72 to +3.59 dtex at the drawing frame stages. This level of precision is adequate for wet-spinners to monitor fiber fineness of input fibers and during the preparation of fibers. The advantage of visNIR spectroscopy is the potential capability of the technique to assess fineness and other important quality characteristics of a fiber sample simultaneously in less than 30 minutes; the disadvantages are the expensive instrumentation and the expertise required for operating the instrument compared to the reference method. These factors need to be considered by the industry before installing an off-line NIR system for predicting quality parameters of input materials and changes in fiber characteristics during mechanical processing.
Flax↗