SEARCH · PubMed Health

Results for “Error minimization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed1997

Investigation of the CasCor Family of Learning Algorithms.

Six learning algorithms are investigated and compared empirically. All of them are based on variants of the candidate training idea of the Cascade Correlation method. The comparison was performed using 42 different datasets from the PROBEN1 benchmark collection. The results indicate: (1) for these problems it is slightly better not to cascade the hidden units; (2) error minimization candidate training is better than covariance maximization for regression problems but may be a little worse for classification problems; (3) for most learning tasks, considering validation set errors during the selection of the best candidate will not lead to improved networks, but for a few tasks it will. Copyright 1997 Elsevier Science Ltd.

Journal Article↗

PubMed2006

Errors in symptom intensity self-assessment by patients receiving outpatient palliative care.

BACKGROUND: Patient-based symptom scores are the standard method for assessment in palliative care. There has been limited research on the frequency of errors upon using this approach. The Edmonton Symptom Assessment Scale (ESAS) is a reliable and valid assessment tool routinely used for symptom intensity assessment in our cancer center. OBJECTIVE: To determine if patients were scoring the symptoms on the ESAS in the way it was supposed to be scored. SETTINGS: The study was carried out at the outpatient palliative care center. DESIGN AND SUBJECTS: Retrospective review of 60 consecutive patient charts was done where the patient had initially scored the ESAS. The physician looked at this scoring on the ESAS and went back to the patient to do the scoring again to see if the patient had scored it in the way it was intended to be scored. The same physician did the assessment on all of the patients. OUTCOME MEASURES: Level of agreement (weighted kappa) before versus after the physician visit; Screening performance of patient completed ESAS for mild and moderate symptom intensity. RESULTS: Complete agreement ranged from 58% (sleep) to 82% (well-being); the weighted kappa ranged from 0.49 (drowsiness) to 0.78 (well-being). There was more agreement for symptoms such as dyspnea, nausea, anxiety, and depression and less agreement for symptoms such as lack of sleep and lack of appetite. The screening performance of the initial patient self assessment showed less sensitivity for nausea, drowsiness if the intensity was mild and less sensitivity for pain, nausea, anxiety, and drowsiness if the intensity was moderate. CONCLUSIONS: Vigilance needs to be maintained about the ESAS scores done by the patients particularly for symptoms of sleep, appetite, and pain. There is a likelihood of error if doctors or nurses do not routinely check the way patients have completed the assessment form. More research is needed to determine the best way to teach patients how to minimize errors in self-reporting of symptoms.

Adult↗

PubMed1990

Factors affecting the Gates' measurement of glomerular filtration rate.

The following technical factors affect the Gates' measurement of glomerular filtration rate (GFR): 1) net injected activity, 2) kidney depth, 3) corrected kidney counts. In the syringe measurement prior to injection, self-attenuation causes 16% data loss for a volume of 0.5 ml if the syringe is positioned perpendicular to the collimator face. A +/- 1 cm error in true kidney depth may cause a 16% difference in GFR in an adult. The choice of the background region of interest (ROI), for background subtraction significantly affects the calculation. To minimize errors in the Gates' estimate of GFR we recommend 1) that syringe counting be done with the syringe parallel to the collimator face; 2) that the i.v. set be included in the postsyringe measurement; in cases of extravasation, the injection site should also be counted; 3) that kidney depth, especially for ectopic and transplanted kidneys be estimated by ultrasound or using lateral views; and 4) that a background ROI for each kidney be used.

Glomerular Filtration Rate↗

PubMed2004

Do earthworms mobilize fixed zinc from ingested soil?

A wide range of organisms inhabit the soil and has to deal with soil-bound metals. The bioavailable fraction of metals may be estimated explicitly using the isotopic dilution technique. In the present paper, we evaluated the isotopic exchange technique for assessing the bioavailability of soil Zn (using 65Zn) to earthworms. To validate the technique, the worms were first exposed to various 65Zn levels, and errors due to soil entrained in the gut were evaluated. This exposure indicated no effect of gamma-radiation on growth (wet weight gain) of the organisms and that depuration of the earthworms minimized errors in labile pools determined by isotopic dilution. Our study further showed that the earthworms accessed 55-65% of the total Zn in the soil. The labile pool for the earthworms Eisenia andrei was similar to that for the plant Lactuca sativa, indicating that earthworms and plants to a large extent access the same fraction of soil Zn. Hence, the isotopic dilution technique has the potential to assess biologically available pool of Zn in soils. As lettuce is not known to significantly mobilize nonlabile metals in soil, this study indicates that Zn uptake by E. andrei is predominantly via the exchangeable pools (possibly the soil pore water) rather than dissolution of Zn held within soil particles or within soil organic matter or other food sources.

Animals↗

PubMed2003

[Why do osteosyntheses fail? The problem with biomechanics and biology].

Avoidance of complications in the course of fracture treatment is of essential importance not only for patients but increasingly from an economic point of view. In the past 15 years emphasis has been placed on the development and fine-tuning of minimally invasive reduction techniques with suitable implants. The main objectives were avoidance of surgical site infection and uneventful fracture healing. This facilitated the solving of long-standing problems but created new sources of error. Minimally invasive, dynamic forms of osteosynthesis were found to fail with extensive open reduction or neglect of biomechanics. Additionally, it appeared that some traditional techniques and basic rules of operative fracture treatment fell into oblivion. The majority of complications are determined already preoperatively by the choice of treatment or implant. After exact analysis of the biomechanics and biological etiology, nonunion is dealt with by an imperative increase in mechanical stability. Additional procedures, i.e., bone graft or debridement, are incorporated into the therapeutic regime. Increasing mechanical stability should be attempted with a minimum of added trauma to avoid local biological impairment. Further improvement of outcome depends on innovative and adapted teaching concepts. Training exclusively with one implant, even under the guidance of the producing company, is insufficient to grasp the various fundamentals of operative fracture treatment indispensable for a successful day-to-day routine.

Biomechanical Phenomena↗

PubMed2005

Diagnostic errors in medicine: a case of neglect.

BACKGROUND: Medical diagnoses that are wrong, missed, or delayed make up a large fraction of all medical errors and cause substantial suffering and injury. Compared with other types of medical error, however, diagnostic errors receive little attention-a major factor in perpetuating unacceptable rates of diagnostic error. Diagnostic errors are fundamentally obscure, health care organizations have not viewed them as a system problem, and physicians responsible for making medical decisions seldom perceive their own error rates as problematic. The safety of modem health care can be improved if these three issues are understood and addressed. SOLUTIONS: Opportunities to improve the visibility of diagnostic errors are evident. Diagnostic error needs to be included in the normal spectrum of quality assurance surveillance and review. The system properties that contribute to diagnostic errors need to be systematically identified and addressed, including issues related to reliable diagnostic testing processes. Even for cases entirely dependent on the skill of the clinician for accurate diagnosis, health care organizations could minimize errors by using system-level interventions to aid the clinician, such as second readings of key diagnostic tests and providing resources for clinical decision support. Physicians need to improve their calibration by getting feedback on the diagnoses they make. Finally, clinicians need to learn about overconfidence and other innate cognitive tendencies that detract from optimal reasoning and learning. CONCLUSION: Clinicians and their health care organizations need to take active steps to discover, analyze, and prevent diagnostic errors.

Diagnostic Errors↗

PubMed1995

A K edge filter technique for optimization of the coherent-to-Compton scatter ratio method.

The ratio method involves forming the ratio of the elastic to inelastic x-ray scatter signals from a localized region of a scattering medium to determine its mean atomic number. An analysis is presented of two major error sources influencing the ratio method: firstly statistical (photon) noise and secondly multiple scattering and self-attenuation of the primary and scatter radiations in the medium. It is shown that a forward scattering geometry minimizes errors of both types for substances composed of elements with low and medium atomic number. However, owing to the small energy separation (approximately 100 eV) of coherent and Compton scatter for this geometry, they cannot be distinguished directly with semiconductor (e.g., Ge) detectors. A novel K edge filter technique is described which permits separation of the elastic and Compton signals in the forward-scatter geometry. The feasibility of this method is demonstrated by experimental results obtained with Ta fluorescence radiation provided by a fluorescent x-ray source filtered with an Er foil. The extension of this technique to the "in vivo" measurement of low momentum transfer inelastic scattering from biological tissues, possibly providing useful diagnostic information, is briefly discussed.

Biophysical Phenomena↗

PubMed1993

Measurement of regional cerebral glucose utilization with fluorine-18-FDG and PET in heterogeneous tissues: theoretical considerations and practical procedure.

Functional tissue heterogeneity, i.e., inclusion of tissues with different rates of blood flow and metabolism within a single region of interest, is an unavoidable problem with PET. Errors in determination of regional cerebral glucose utilization (rCMRglc) with [18F]FDG have resulted from the currently used simplifying assumption that all regions examined are homogeneous. We have established an optimal, yet practical procedure to minimize errors due to tissue heterogeneity in determination of rCMRglc. Effects of applying the three-rate constant kinetic model designed for homogeneous tissues with both dynamic and single-scan procedures and the Patlak plot were evaluated in normal subjects in experimental periods up to 120 min following tracer injection. The procedure with a single scan carried out any time within the interval between 60 and 120 min following tracer injection, combined with population average rate constants determined over a 120-min period, was found to be optimal for quantitative rCMRglc studies.

Adult↗

PubMed2001

Rapid spectrophotometric determination of red and yellow isochromic carotenoid fractions in paprika and red pepper oleoresins.

A rapid method has been developed for the determination of the red (R) and yellow (Y) isochromic carotenoid pigments fractions in paprika and oleoresins, based on UV-visible spectrophotometric measurement at two characteristic wavelengths and application of the Lambert-Beer law for multicomponent mixtures. The wavelengths 472 and 508 nm were selected as the most appropriate for simultaneous quantification of these fractions in the acetone extract of pigments. Experimental determination of the specific absorption coefficients (epsilon) for the two pigment fractions (R, Y) at 472 and 508 nm yielded equations to calculate the concentration of the two fractions, the total pigment content, and the ratio between the two fractions. The error in the determination of the isochromic fractions by the proposed spectrophotometric method was <5% when the results were compared with those obtained by HPLC analysis. The method can be applied to the direct extract of pigments, thereby avoiding saponification and minimizing errors from pigment degradation and sample manipulation as well as shortening the time of analysis (5 min in the case of oleoresins).

Capsicum↗

PubMed2000

Accuracy considerations when using early (four- or six-hour) radioactive iodine uptake to predict twenty-four-hour values for radioactive iodine dosage in the treatment of Graves' disease.

Although literature has offered methods to predict 24-hour radioactive iodine uptake values from early (4- to 6-hour) measurements, the resultant dosage errors have not been examined. Potential errors include underdosage, overdosage, and a failure to recognize rapid turnover patients (early-to-late uptake ratios > or = 1) who are at high risk for treatment failure and full-body radiation exposure. We developed and tested a novel method for minimizing error involved in using a single early uptake measurement to derive late uptake. From a retrospective analysis of 203 Graves' disease patients, receiver operating characteristic (ROC) curve analysis enabled us to identify patients likely to experience rapid turnover and therefore should receive 24-hour studies. Twenty-four-hour uptake measurements are necessary with 77% or more 4-hour uptake values and 80% or more 6-hour values. After eliminating these patients, we developed linear regression equations to predict the 24-hour uptake from 4-hour (n = 61) and 6-hour (n = 22) rule groups, testing their efficacy on separate 4-hour (n = 61) and 6-hour (n = 21) patient groups. We also used our test population to measure error in four early-to-late uptake conversion formulas presented in the literature. Error involved in these predictions ranged from a 10.6% overestimate for 4-hour calculations to a 5.9% underestimate for 6-hour calculations. When applied to two dosage formulas incorporating gland size, absorbed dose, and 24-hour uptake, average dosage error was 7%. In comparison to the other sources of error radioactive iodine (131I) dosimetry, potential error in predicting 24-hour uptake from 4- or 6-hour uptake values is low.

Graves Disease↗

PubMed2000

Temperature variation and distribution of living cells within tree stems: implications for stem respiration modeling and scale-up.

Few studies have examined variation in respiration rates within trees, and even fewer studies have focused on variation caused by within-stem temperature differences. In this study, stem temperatures at 40 positions in the stem of one 30-year-old Norway spruce (Picea abies (L.) Karst.) were measured during 40 days between July 1994 and June 1995. The temperature data were used to simulate variations in respiration rate within the stem. The simulations assumed that the temperature-respiration relationship was constant (Q10 = 2) for all days and all stem positions. Total respiration for the whole stem was calculated by interpolating the temperature between the thermocouples and integrating the respiration rates in three dimensions. Total respiration rate of the stem was then compared to respiration rate scaled up from horizontal planes at the thermocouple heights (40, 140, 240 and 340 cm) on a surface area and on a sapwood volume basis. Simulations were made for three distributions of living cells in the stems: one with a constant 5% fraction of living cells, disregarding depth into the stem; one with a living cell fraction decreasing linearly with depth into the stem; and one with an exponentially decreasing fraction of living cells. Mean temperature variation within the stem was 3.7 degrees C, and was more than 10 degrees C for 8% of the time. The maximum measured temperature difference was 21.5 degrees C. The corresponding mean variation in respiration was 35% and was more than 50% for 24% of the time. Scaling up respiration rates from different heights between 40 and 240 cm to the whole stem produced an error of 2 to 58% for the whole year. For a single sunny day, the error was between 2 and 72%. Thus, within-stem variations in temperature may significantly affect the accuracy of scaling respiration data obtained from small samples to whole trees. A careful choice of chamber position and basis for scaling is necessary to minimize errors from variation in temperature.

Body Temperature↗

PubMed2000

Medical students' errors in pharmacotherapeutics.

OBJECTIVES: This study analysed the errors made by 16 final-year medical students in a classroom prescribing exercise. The aim was to gain greater understanding of the reasons for non-optimal prescribing and of how to improve basic training in pharmacotherapeutics. METHODS: The task was to adjust a patient's phenytoin sodium dosage to achieve better control of seizures. It was based on a real-life case, and was presented as a written exercise. Process-tracing and think-aloud techniques were used to study the students' performance. RESULTS: The results suggest that the root cause of the errors was lack of a knowledge base which integrated scientific knowledge with clinical know-how. Three different clinical reasoning strategies were observed. Students who followed an incremental strategy demonstrated superior scientific knowledge and this resulted in less hazardous errors. Those who followed gambling or backward-reasoning strategies appeared to possess inferior scientific knowledge and this resulted in more hazardous errors. CONCLUSIONS: The results support current trends towards integrating basic medical science into a foundation of clinical know-how, as in the problem-based curriculum. They also emphasize the importance of a thorough grounding in medical science as a means of minimizing error.

Clinical Competence↗

PubMedDate not supplied

[Evaluation of electronic drug prescriptions at a university hospital].

The medical orders have an important role in the prevention of medication errors. The objective of this study is to identify and to analyse the causal factors of error in the medication related to electronic prescription in two different clinics of a university hospital of the interior of the state of São Paulo. A questionnaire related to the advantages and disadvantages of electronic prescription was applied to the professionals of these clinics. The data collected was grouped in accordance with the similarity of the answers. These professionals identified causal factors of errors in the medical orders, but they also mentioned the advantages of it when compared to the manual order, such as bigger readability, rapidity and organization of the first one. As we can see, the computerized system of medical order represents a great advance considering strategies to minimize errors from orders badly formulated. However, it does not eliminate the possibility of occurrence of causal factors of errors in the medication, which asks for some modifications in the system.

Attitude of Health Personnel↗

PubMed1998

Quantitative information of specific diagnostic tests.

The goal of diagnostic testing is to maximize information (I) of a specific disease of interest (D) resulting from the performance of a specific diagnostic test procedure (T). However, all tests suffer from errors which result in incomplete information and inaccurate diagnostic conclusions. The methods of Information Theory have successfully solved a range of signal transmission problems involving physical systems operating under conditions of noise. Medical testing procedures were found to be analogous to noisy systems; hence, Information Theory methods were applied to minimize errors in diagnostic testing. Prior to performing a diagnostic test, the quantity of information, Apriori Information (ID), regarding the presence or absence of the disease was only a function of the prevalence (P) of disease in the population. After performing a diagnostic test, the quantity of information, Aposteriori Information (IDIT) was a function of not only P but also the test sensitivity (A) and test specificity (B). The quantity of information gained by test performance was computed from the difference between aposteriori and apriori information. delta I = IDIT - ID To illustrate the relationship between pretest, apriori, and post-test, aposteriori, information the values of ID and IDIT were computed for five common cardiovascular tests applied to populations with different coronary artery disease prevalence. This cross-sectional analysis studied the quantitative information obtained from Electrocardiography (ECG), Bicycle Ergometer Stress Tests (BEST), Stress-Echo Ergometer Tests (SEET), Thallium 201 Stress Tests (ThST), and Coronary Arteriography (CorA). Apriori information ranged from a minimum of 0 (for prevalence = 0.5) to a maximum of 1.0 (for prevalence = 0 or 1.0) The aposteriori information was computed for all apriori information and occupied the range between that of a "perfect" test (A = 1.0 and B = 1.0) and that of a "worthless" test (A = 0.5 and B = 0.5). All tests demonstrated greater information gain when apriori information was minimal; Little additional information could be gained when the apriori information was close to certainty (i.e., for prevalence near 0 or 1.0). Electrocardiography demonstrated little significant IDIT at any value of ID. Thallium 201 stress tests provided similar aposteriori information values to those of Stress-Echo Ergometer Stress and either demonstrated greater information gain than Bicycle Ergometer Stress Tests. Coronary Arteriography provided the maximum values of aposteriori information. Information Theory methods provided an effective quantitative method to compare the effectiveness of diagnostic tests over a wide range of disease prevalence.

Adult↗

PubMed1995

The use of multiple-choice tests in anatomy: common pitfalls and how to avoid them.

Multiple-choice questions (MCQ) are widely used to evaluate students in the health sciences, including anatomy. Unusual responses in 90 simple MCQ examinations have been identified and classified as to cause, including a number of illustrated examples. About one-quarter of these errors were attributable to the teacher and could have been avoided by a critical analysis of the questions before use. The increasing use of sophisticated formats of the MCQ in medical education indicates that teachers need to analyze their questions more carefully before and after actual tests to minimize errors.

Anatomy↗

PubMed2005

DNA barcoding: error rates based on comprehensive sampling.

DNA barcoding has attracted attention with promises to aid in species identification and discovery; however, few well-sampled datasets are available to test its performance. We provide the first examination of barcoding performance in a comprehensively sampled, diverse group (cypraeid marine gastropods, or cowries). We utilize previous methods for testing performance and employ a novel phylogenetic approach to calculate intraspecific variation and interspecific divergence. Error rates are estimated for (1) identifying samples against a well-characterized phylogeny, and (2) assisting in species discovery for partially known groups. We find that the lowest overall error for species identification is 4%. In contrast, barcoding performs poorly in incompletely sampled groups. Here, species delineation relies on the use of thresholds, set to differentiate between intraspecific variation and interspecific divergence. Whereas proponents envision a "barcoding gap" between the two, we find substantial overlap, leading to minimal error rates of approximately 17% in cowries. Moreover, error rates double if only traditionally recognized species are analyzed. Thus, DNA barcoding holds promise for identification in taxonomically well-understood and thoroughly sampled clades. However, the use of thresholds does not bode well for delineating closely related species in taxonomically understudied groups. The promise of barcoding will be realized only if based on solid taxonomic foundations.

Animals↗

PubMed2001

[AIDS patients' compliance with antiretroviral treatment: notified difficulties and measures for improvement at a teaching hospital].

This study aimed at identifying the incidence of drug intake errors and the main therapy-related difficulties among AIDS patients as well as at proposing measures to increase patients' adherence to treatment. Sixty-one patients with AIDS assisted by the University Hospital of São Paulo State University at Campinas were interviewed. The most frequent errors concerned the combinations of drugs and the length of fasting. The difficulties reported were adverse effects and the variety of drugs. Based on these data, the authors proposed the use of an illustrated guide for drug-related information. It is hoped that individualized guidance can contribute to minimize errors concerning adherence to therapy.

Acquired Immunodeficiency Syndrome↗

PubMed2002

Assessing allelic dropout and genotype reliability using maximum likelihood.

A growing number of population genetic studies utilize nuclear DNA microsatellite data from museum specimens and noninvasive sources. Genotyping errors are elevated in these low quantity DNA sources, potentially compromising the power and accuracy of the data. The most conservative method for addressing this problem is effective, but requires extensive replication of individual genotypes. In search of a more efficient method, we developed a maximum-likelihood approach that minimizes errors by estimating genotype reliability and strategically directing replication at loci most likely to harbor errors. The model assumes that false and contaminant alleles can be removed from the dataset and that the allelic dropout rate is even across loci. Simulations demonstrate that the proposed method marks a vast improvement in efficiency while maintaining accuracy. When allelic dropout rates are low (0-30%), the reduction in the number of PCR replicates is typically 40-50%. The model is robust to moderate violations of the even dropout rate assumption. For datasets that contain false and contaminant alleles, a replication strategy is proposed. Our current model addresses only allelic dropout, the most prevalent source of genotyping error. However, the developed likelihood framework can incorporate additional error-generating processes as they become more clearly understood.

Alleles↗