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PubMed1989

Eyewitness accuracy and confidence: within- versus between-subjects correlations.

Previous researchers using between-subjects comparisons have found eyewitness confidence and accuracy to be only negligibly correlated. In this study, we examined the predictive power of confidence in within-subject terms. Ninety-six subjects answered, and made confidence ratings for, a series of questions about a crime they witnessed. The average between-subjects and within-subject accuracy-confidence correlations were comparably low: r = .14 (p less than .001) and r = .17 (p less than .001), respectively. Confidence is neither a useful predictor of the accuracy of a particular witness nor of the accuracy of particular statements made by the same witness. Another possible predictor of accuracy, response latency, correlated only negligibly with accuracy (r = -.09 within subjects), but more strongly with confidence (r = -.27 within subjects). This pattern was obtained for both between-subjects and within-subject comparisons. The theoretical and practical implications of these results are discussed.

Adult↗
PubMed1995

On the accuracy of personality judgment: a realistic approach.

The "accuracy paradigm" for the study of personality judgment provides an important, new complement to the "error paradigm" that dominated this area of research for almost 2 decades. The present article introduces a specific approach within the accuracy paradigm called the Realistic Accuracy Model (RAM). RAM begins with the assumption that personality traits are real attributes of individuals. This assumption entails the use of a broad array of criteria for the evaluation of personality judgment and leads to a model that describes accuracy as a function of the availability, detection, and utilization of relevant behavioral cues. RAM provides a common explanation for basic moderators of accuracy, sheds light on how these moderators interact, and outlines a research agenda that includes the reintegration of the study of error with the study of accuracy.

Humans↗
PubMed1999

Diagnosis of pigmented skin lesions by epiluminescence microscopy: determinants of accuracy improvement in a nationwide training programme for practical dermatologists.

BACKGROUND: The poor accuracy of the clinical examination of pigmented skin lesions (PSLs) is a major limitation of secondary prevention strategies for cutaneous melanoma (CMM). In the last few years, the epiluminescence microscopy (ELM) technique has been used increasingly as an adjunct to clinical examination in the dermatology practice. Although the question of training has emerged as a priority, the diffusion, the effects, and the correlates of educational programmes in ELM have seldom been studied. METHODS: Thirty ELM images of PSLs (11 CMMs, 14 melanocytic nevi (MN), and 5 nonmelanocytic lesions (NMLs) each matched with the corresponding clinical or plain photographic image were independently diagnosed before and after a one-day workshop by 83 Italian dermatologists participating in a nationwide educational programme on ELM. The original histology diagnosis was assumed as a gold standard. The overall effect of training on a set of accuracy measures by PSL type was evaluated. The association of the professional sector (public/private), number of years of general experience in dermatology (1-10/>10), average weekly number of PSLs seen (< or =10/11-20/>20), routine use of ELM (no/yes), and area of residence (northern/southern Italy) with the mean number of PSLs correctly diagnosed before and after training was evaluated with the general factorial analysis of variance. The factors associated with improvement between the two tests were evaluated with the analysis of variance for repeated measures. RESULTS: Compared with pretraining data, the average percentage of exact diagnosis increased significantly for all PSLs (CMMs, 72% vs 55%; MN, 68% vs 64%; NMLs, 67% vs 58%; total lesions combined, 69% vs 60%). Baseline as well as final accuracy were independent from the professional sector and the years of experience but were greater among those subjects who reported >20 PSLs per week compared with the reference group (< or =10 PSLs). The routine use of ELM was associated with a slight advantage in pretraining accuracy. The area of residence was the strongest determinant of baseline as well as final accuracy. The effect of training was independent from all factors studied with the exception of the area of residence with a 13% increase in the frequency of exact diagnosis in northern Italy (from 66-79%) and 6% in southern Italy (from 55-61%). CONCLUSIONS: Though insufficient in absolute terms, a measurable increase in ELM accuracy can be achieved even with intense training sessions of short duration. Medical education to ELM in southern Italy should be a priority.

Clinical Competence↗
PubMed1999

The QA pressure measurement system: an accuracy and reliability study.

OBJECTIVE: The main purpose of this study was to determine the accuracy and reliability of the Queen Alexandra Pressure Measurement System (QA PMS). Furthermore, we examined whether there were significant differences in measured pressures of the buttock area during sitting between normal subjects and spinal cord injured (SCI) patients. DESIGN: Accuracy (calibration) and reliability (test-retest) study. SETTING: The spinal cord unit of Tertiary Care Centre 'De Hoogstraat' in Utrecht, The Netherlands. PATIENTS: A convenience sample of 16 SCI patients and 15 normal subjects. MAIN OUTCOME MEASURES: The accuracy was determined by using the Standard Error of the Mean (SEM, in mmHg). The Technical Error of Measurement (TEM, in mmHg) was calculated as measure for differences between two paired measurements. The reliability was determined by using an Intraclass Correlation Coefficient (ICC). Significant differences in measured pressures between both groups (P<0.05) were determined by using an unpaired (two sample) t-test. RESULTS: Accuracy (calibration): mean SEM=0.30 (+/-0.1) mmHg, indicating a high level of accuracy. Differences between two paired measurements: mean TEM calibration= 1.87 (+/-0.76) mmHg; mean TEM normal subjects=4.76 (+/-1.78) mmHg; mean TEM SCI patients=6.34 (+/-2.19) mmHg. Reliability: mean ICC(3,1) calibration=0.85 (95% CI=0.74 0.95); mean ICC(2.1) normal subjects=0.92 (95% CI=0.90 0.94); mean ICC(2.1) SCI patients=0.90 (95% CI=0.88 0.92). The normal subjects had significantly higher mean pressures (P=0.028) than the SCI patients (mean pressures 31.0 vs 28.5 mmHg), whilst the SCI patients had significantly higher peak-pressures (P=0.0000) than the normal subjects (mean peak-pressures: 134.1 vs 75.7 mmHg). CONCLUSIONS: The QA Pressure Measurement System has sufficient accuracy and good reliability as a measurement procedure. There are significant differences between the measured pressures of both groups: the significantly higher peak pressures of the SCI patients seem to be the most important.

Buttocks↗
PubMed2004

The influence of multiple presentations on judgments of children's phonetic accuracy.

Two experiments examined whether listening to multiple presentations of recorded speech stimuli influences the reliability and accuracy of judgments of children's speech production accuracy. In Experiment 1, 10 listeners phonetically transcribed words produced by children with phonological impairments after a single presentation and after the word was played 7 times. Inter- and intratranscriber reliability in the single- and multiple-presentation conditions did not differ significantly. In Experiment 2, 18 listeners provided binary correct/incorrect judgments of /s/ accuracy in single- and multiple-presentation conditions. There was no systematic effect of presentation condition on either accuracy or intrarater reliability. However, greater interrater reliability was noted in the multiple-presentation condition, particularly for tokens of /s/ that were incorrect or acoustically intermediate between an incorrect and a correct /s/. Taken together, the results suggest that multiple presentations have no measurable effect on the accuracy and intrarater reliability of judgments of children's phonetic accuracy, but that they do have a small effect on interrater reliability. Clinical implications are discussed.

Adult↗
PubMed2001

[CT-guided percutaneous core biopsy: Effective accuracy, diagnostic utility and effective costs].

PURPOSE: The value of a diagnostic technique does not only depend on its sensitivity, specificity and accuracy, but also on how its results affect clinical management. This effect is represented by the values effective accuracy and the diagnostic utility which were determined for CT-guided coaxial core biopsies in this study. MATERIALS AND METHODS: 180 consecutive biopsies were analyzed. The results were analyzed with the help of a logistic regression analysis with regard to the organ regions biopsied, the size of the needle used, and the number of tissue cores taken. Correct results that were not accepted as diagnostic clinically and resulted in additional biopsies were scored together with the false results under negative utility coefficients. RESULTS: The sensitivity, specificity and accuracy of all the tests amounted to 91.1 %, 100 %, and 93.3 %, respectively. The diagnostic utility of the biopsies varied between 66 % for the liver and pancreatic lesions, and 88 % for the non-organ related retroperitoneum. In those cases where more than three tissue cores were taken the results were statistically significantly better in terms of effective accuracy and diagnostic utility. No significant differences were found with regard to different needle sizes in the biopsied organ regions. The lowest clinical acceptance was observed for the histological findings "scar tissue" and "inflammation". CONCLUSION: CT-guided coaxial biopsies offer a high degree of sensitivity, specificity and accuracy, as well as a low rate of therapeutically relevant complications. With increasing use of differentiated strategies in therapy for malignomas percutaneous biopsies play a very important role in the management of these diseases. Prospective studies should further evaluate the effective accuracy and diagnostic utility of core biopsies also in comparison to fine needle aspiration biopsies (FNAP).

Adult↗
PubMed2004

Influence of tumor characteristics on the accuracy of endoscopic ultrasonography in staging cancer of the esophagus and esophagogastric junction.

BACKGROUND AND STUDY AIMS: Endoscopic ultrasonography (EUS) is the most accurate method of assessing the locoregional extent of cancer of the esophagus and esophagogastric junction. The aim of this study was to evaluate the influence of tumor-related factors such as length and location on the accuracy of EUS in staging these tumors. PATIENTS AND METHODS: Between January 1997 and September 2002, 280 consecutive patients underwent preoperative EUS for staging cancer of the esophagus and esophagogastric junction. The influence of histopathology, the presence of Barrett's dysplasia or stenosis, and the location and length of the primary tumor on the accuracy of EUS for T, N, and M staging were studied. RESULTS: The overall accuracy rates of EUS for assessing the T, N, and M stages were 73 %, 80 %, and 78 %, respectively. The influence of the tumor's histopathology and the presence of Barrett's dysplasia or stenosis was minimal. The accuracy of EUS was greater in tumors 5 cm or less in size than in tumors larger than 5 cm (82 % vs. 52 % for the T stage, P < 0.05; 88 % vs. 59 % for the N stage, P < 0.05; and 92 % vs. 56 % for the M stage, P < 0.001). The low accuracy of T staging in larger tumors may be due to the exclusion of patients with local unresectability or distant metastases. EUS was also significantly better in esophageal tumors, particularly for identifying celiac trunk metastases (93 % vs. 63 %; P < 0.001). CONCLUSIONS: The accuracy of EUS for staging esophageal cancer is lower in tumors larger than 5 cm and in esophagogastric junction tumors than in tumors 5 cm in size or less and in esophageal tumors. These findings should be considered when treatment decisions are being taken.

Adenocarcinoma↗
PubMed1993

An accuracy center in the ribosome conserved over 2 billion years.

The accuracy of translation in Escherichia coli is profoundly influenced by three interacting ribosomal proteins, S12, S4, and S5. Mutations at lysine-42 of S12, originally isolated as causing resistance to streptomycin, increase accuracy. Countervailing "ribosomal ambiguity mutations" (ram) in S4 or S5 decrease accuracy. In the eukaryotic ribosome of Saccharomyces cerevisiae, mutations in SUP46 and SUP44, encoding the proteins equivalent to S4 and S5, lead to omnipotent suppression--i.e., to less accurate translation. The evolution of ribosomal protein S12 can be traced, by comparison with archaebacteria and Tetrahymena, to S28 of S. cerevisiae, even though the two proteins share only very limited regions of homology. However, one region that has been conserved contains a lysine residue whose mutation leads to increased accuracy in E. coli. We have introduced into S28 of yeast the same amino acid substitutions that led to the original streptomycin-resistant mutations in E. coli. We find that they have a profound effect on the accuracy of translation and interact with SUP44 and SUP46, just as predicted from the E. coli model. Thus, the interplay of these three proteins to provide the optimal level of accuracy of translation has been conserved during the 2 billion years of evolution that separate E. coli from S. cerevisiae.

DNA↗
PubMed2006

On the proper use of mass accuracy in proteomics.

Mass measurement is the main outcome of mass spectrometry-based proteomics yet the potential of recent advances in accurate mass measurements remains largely unexploited. There is not even a clear definition of mass accuracy in the proteomics literature, and we identify at least three uses of this term: anecdotal mass accuracy, statistical mass accuracy, and the maximum mass deviation (MMD) allowed in a database search. We suggest using the second of these terms as the generic one. To make the best use of the mass precision offered by modern instruments we propose a series of simple steps involving recalibration of the data on "internal standards" contained in every proteomics data set. Each data set should be accompanied by a plot of mass errors from which the appropriate MMD can be chosen. More advanced uses of high mass accuracy include an MMD that depends on the signal abundance of each peptide. Adapting search engines to high mass accuracy in the MS/MS data is also a high priority. Proper use of high mass accuracy data can make MS-based proteomics one of the most "digital" and accurate post-genomics disciplines.

Mass Spectrometry↗
PubMed2001

The accuracy of self-reported weight by overweight and obese women in an outpatient setting.

OBJECTIVE: To investigate the accuracy of self-reported weight of overweight and obese women and characterisation of under-, correct- and over-reporters based on a number of related variables. DESIGN: Weight was self-reported before entering the study. At baseline, actual weight was recorded, and demographic, health, nutritional, psychological and physical activity questionnaires were completed. SETTING: A hospital outpatient department. SUBJECTS: Participants were 131 women aged 18-64 years with a body mass index attending a Comprehensive Weight Management Programme. OUTCOME MEASURES: The accuracy of self-reported weight was investigated for the total group, and the subjects were then categorised into three groups according to accuracy of self-reported weight (under-, correct- and over-reporters). The relationship between these accuracy groups and demographic, health, nutritional, and psychological variables and physical activity was examined, to characterise the under-, correct- and over-reporters. RESULTS: Although not statistically significantly different, the total group of women tended to underestimate their weight by 0.8 (+/-3.6) kg. Categorisation according to the accuracy groups revealed that 29% underestimated their weight by 2 kg or more, 19% overestimated their weight by 2 kg or more, and only 52% correctly estimated their weight within 2 kg. Some trends and statistically significant differences between the accuracy groups concerning certain variables, e.g. height, age, income, education, contraceptive pill usage, smoking and food choices were evident. CONCLUSIONS: Self-reported weight of a group of overweight/obese individuals may be a valid and reliable indicator of actual weight, but self-reported weight of an overweight/obese individual can not be interpreted similarly. Further research is necessary to ensure reliable characterisation of under-, over- and correct reporters.

Adolescent↗
PubMedDate not supplied

Effect of time of day on the accuracy and consistency of the badminton serve.

In badminton, the short doubles serve requires accuracy, whereas the long singles serve also requires power. The present study investigated if there are time-of-day effects for these two types of serve. Eight male badminton players completed two familiarization sessions before being tested at 08:00, 14:00 and 20:00 hours, the session times being counterbalanced. At each session, subjects performed ten warm-up serves, followed by ten short and ten long test serves. A 1 m2 yellow grid was placed at the front of the recipient's service box (short serve) or at the back of the court along the centre line (long serve). Subjects scored 'hits' with their serves by putting the shuttle in the grid as close as possible to one corner of the target grids. Accuracy was assessed by calculating the average radial error (RE) of the serves, and consistency by calculating the standard deviation of the RE. Data were analysed by ANOVA. There was a time of day effect for temperature (p < 0.0005) and a trend in this for grip strength (p = 0.052). The accuracy of the 'hits' was highest at 14:00 hours (p < 0.05) and the short serve showed greater accuracy than the long serve (p < 0.0005). There was a significant effect of serve number with the short serve, subjects getting more accurate with later serves (p = 0.036). No significant variation in consistency was found (p > 0.05). In summary, the lack of agreement in profiles for temperature and the accuracies of long and short service suggests that some factor(s) that deteriorate during the course of the time spent awake might be involved, in addition to body temperature, in determining accuracy in the tasks measured.

Adult↗
PubMed1990

Speed-accuracy tradeoff during response preparation.

The speed-accuracy operating curve was investigated in a movement precuing two- or four-choice reaction time task. Four levels of response preferences were manipulated with subject instructions and postresponse information: (a) accuracy, (b) reaction time latency, (c) accuracy and reaction time latency, and (d) no preference. Eighty subjects completed 480 discrete keypressing responses with the index and middle fingers of both hands. The mixed design mean reaction time analysis indicated faster performances for the reaction time latency and the accuracy and reaction time latency groups than the no preference group. Additionally, the percent correct analysis revealed two significant interactions: (a) Trial Block x Precue x Response Preference, and (b) Delay x Precue x Hand Position. Overall, the present findings provide partial support for the speed-accuracy operating curve predictions. Caution is advised when drawing chronometric inferences based only on reaction time data or when response accuracies are extremely high.

Analysis of Variance↗
PubMed2004

Accuracy of microCT in the quantitative determination of the degree and distribution of mineralization in developing bone.

PURPOSE: To evaluate the accuracy and applicability of a commercially available microCT system for comparative measurements of the degree and distribution of mineralization of developing bone. MATERIAL AND METHODS: Homogeneous K2HPO4 solutions with different concentrations (range 0-800 mg/cm3) were used to assess the accuracy of a microCT system equipped with a polychromatic X-ray source. Both high (45 kV) and low (70 kV) tube peak voltages were explored. The resulting attenuation was compared with calculated theoretical attenuation values to estimate the accuracy. As an example of its applicability, the method was used to assess changes in the degree of mineralization of various regions of the mandible from two pigs of different developmental age. RESULTS: On average, the estimated error of the measured linear attenuation was 10% or less. Accuracy was dependent on the average mineral concentration, the size of the sample, and the energy of the X-ray beam. The accuracy of the microCT system appeared sufficient to distinguish regional differences in the degree of mineralization within and between specimens of developing mandibular bone. Furthermore, the resolution of the system allowed identification of different degrees of mineralization within trabeculae. CONCLUSION: Accuracy of microCT with polychromatic radiation can be considered adequate for assessment of the degree of mineralization of developing bone. Therefore, this method provides a three-dimensional means by which to simultaneously investigate the bone structure as well as the degree of mineralization during development in a non-destructive manner and with high resolution.

Animals↗
PubMed2005

Accuracy of the modified Continuous Glucose Monitoring System (CGMS) sensor in an outpatient setting: results from a diabetes research in children network (DirecNet) study.

OBJECTIVE: We previously reported the results of an inpatient accuracy study in children with type 1 diabetes using the Continuous Glucose Monitoring System (CGMS, Medtronic MiniMed, Northridge, CA). During the course of that study, a new process was implemented for manufacturing the CGMS sensor. Accuracy from the resulting modified sensor used by only 14 children was significantly better than the original version [median relative absolute difference (RAD), 11% vs. 19%; P < 0.001]. Baseline data from a subsequent outpatient study provide an opportunity to further assess the accuracy of the modified sensor in a much larger sample of children with type 1 diabetes. RESEARCH DESIGN AND METHODS: As part of a randomized trial to assess the utility of the GlucoWatch G2 Biographer (Cygnus, Inc., Redwood City, CA), 200 children with type 1 diabetes were instructed to wear a CGMS for 48-72 h in an outpatient setting at baseline. Glucose measurements from a OneTouch UltraSmart (Lifescan, Inc., Milpitas, CA) home glucose meter were downloaded and used as reference values to calculate accuracy measures. RESULTS: The overall median RAD was 12%. Accuracy was better during hyperglycemia than during hypoglycemia (median RAD, 10% vs. 20%; P < 0.001) and on optimal versus non-optimal days but did not vary significantly by the number of calibrations entered. CONCLUSIONS: These data confirm the improved accuracy previously reported for the modified version of the CGMS sensor.

Blood Glucose↗
PubMed2003

Longitudinal changes in the accuracy of reported energy intake in girls 10-15 y of age.

BACKGROUND: Dietary records are often used to estimate individual energy needs and population energy requirements. However, significant underreporting of total energy intake (EI) has been found when EI is compared with total energy expenditure (EE) measured by doubly labeled water. OBJECTIVE: This study aimed to determine whether the accuracy of reported EI decreases from middle childhood to adolescence. DESIGN: In this longitudinal study of 26 healthy girls, EI and EE were measured at ages 10, 12, and 15 y. Accuracy of reported EI (EI/EE x 100%) was calculated at each age. At study entry, girls had a mean (+/- SD) body mass index (in kg/m(2)) of 16.8 +/- 1.9 and percentage body fat of 24.0 +/- 4.6%. Measurements of EI were a 7-d dietary record and those of EE were by doubly labeled water. RESULTS: As they got older, girls tended to report EI less accurately: the average accuracy was 88 +/- 13% at age 10 y, 77 +/- 21% at age 12 y, and 68 +/- 17% at age 15 y. The declines in reporting accuracy from age 10 y to age 12 y and from age 10 y to age 15 y were statistically significant (P = 0.03 and P = 0.001, respectively). Reporting accuracy also declined from age 12 to age 15 y but not significantly. When percentage body fat was added to the model, results were essentially unchanged. CONCLUSION: Because of the decline in EI reporting accuracy with age, the use of EI data obtained from dietary records in adolescent girls will result in substantial underestimation of energy needs.

Adolescent↗
PubMed1988

Accuracy and reliability of nutrient intake estimates.

A common problem in nutrition assessment is determining the number of days of food intake information required to obtain accurate estimates of nutrient intakes. A standard definition of accuracy is needed for clinical practice and nutrition research. Any measure of accuracy should have two properties: 1) accuracy should improve as the number of observations increases and 2) the number of observations needed to achieve a given degree of accuracy should be unaffected by changes in the scale of measurement. Two approaches to defining accuracy are presented, one based on a proportion of the mean and the other using a proportion of the standard deviation (SD). The concept of reliability of measurement is introduced along with equations and tables that can be used in determining the number of repeated food records needed for a particular purpose. Defining accuracy in terms of the variability and reliability shows that increasing the number of days of a food record has a quickly diminishing return. For most purposes, 3-14 d of food diary records per subject will prove adequate.

Data Collection↗
PubMed1988

Effect of combining electrocardiographic interpretation results on diagnostic accuracy.

In order to test the diagnostic performance of various ECG computer programs a reference library of ECGs is being established and evaluation methods are being developed in an international co-operative project. A pilot study was undertaken in which 250 validated electrocardiograms (ECG) and vectorcardiograms (VCG) comprising seven diagnostic groups i.e., normal, left, right and bi-ventricular hypertrophy, anterior, inferior and combined infarction have been analysed independently by 11 different computer programs as well as by six cardiologists. A coding scheme was applied to assign individual diagnostic statements to a common set and to obtain combined program and cardiologist interpretation results. Preliminary results indicate that the accuracy of classification by different programs varies widely. Total accuracy varied between 57.2% and 75.8% (median 69.4%). The cardiologists had a higher accuracy (median 74.3%) than the majority of programs, at least when using the standard ECG. As it is considered premature to stress individual program results, in view of the current sample size, the enhancement in diagnostic accuracy obtained by combining interpretation results is highlighted. Indeed combined cardiologist and program results demonstrated the highest accuracy i.e., respectively 78.7% and 76.1%, higher than the result of any individual reader or program. The combined result of the five most accurate programs was 78.4%, that of the six least accurate was 71.5%, which is again higher than the respective individual components. These findings demonstrate that the combination of expert knowledge of computer programs can, similar to panel review and group analysis in clinical practice, enhance diagnostic accuracy.

Diagnosis, Computer-Assisted↗
PubMed2002

Accuracy and power of bayes prediction of amino acid sites under positive selection.

Bayes prediction quantifies uncertainty by assigning posterior probabilities. It was used to identify amino acids in a protein under recurrent diversifying selection indicated by higher nonsynonymous (d(N)) than synonymous (d(S)) substitution rates or by omega = d(N)/d(S) > 1. Parameters were estimated by maximum likelihood under a codon substitution model that assumed several classes of sites with different omega ratios. The Bayes theorem was used to calculate the posterior probabilities of each site falling into these site classes. Here, we evaluate the performance of Bayes prediction of amino acids under positive selection by computer simulation. We measured the accuracy by the proportion of predicted sites that were truly under selection and the power by the proportion of true positively selected sites that were predicted by the method. The accuracy was slightly better for longer sequences, whereas the power was largely unaffected by the increase in sequence length. Both accuracy and power were higher for medium or highly diverged sequences than for similar sequences. We found that accuracy and power were unacceptably low when data contained only a few highly similar sequences. However, sampling a large number of lineages improved the performance substantially. Even for very similar sequences, accuracy and power can be high if over 100 taxa are used in the analysis. We make the following recommendations: (1) prediction of positive selection sites is not feasible for a few closely related sequences; (2) using a large number of lineages is the best way to improve the accuracy and power of the prediction; and (3) multiple models of heterogeneous selective pressures among sites should be applied in real data analysis.

Amino Acid Substitution↗