Accuracy Of Visual Estimation Research Articles

Standard area diagrams for pecan leaf scab: Effect of rater experience and location, and leaf size on reliability and accuracy of visual estimates.

Assessments of the severity of scab (Venturia effusa), an economically significant disease of pecan, are critical for determining pecan cultivar susceptibility, disease epidemiology, and integrated disease management approaches. We developed a standard area diagram (SAD) set to aid in assessments of pecan leaflet scab. Leaflets with scab lesions were harvested and scanned using a flatbed scanner at 600 dpi, and Fiji (ImageJ) was used to determine the actual percent disease severity. The SADs had 10 leaflets ranging in severity from 0.2 to 48.9%. Forty 'small' (1.34 - 7.43 cm2) and forty 'large' (7.67 - 25.9 cm2) leaflet images were randomized for rater assessments. The images were assessed twice by 36 raters, first without and then with the SADs as a guide. Data were subjected to analysis using Lin's Concordance Correlation Coefficient (LCC, pc) to determine the accuracy of ratings, and by Intra-class Correlation Coefficient analysis to determine inter-rater reliability. The effects of rater experience, rater location, and leaflet size were also determined. The SADs significantly improved the agreement between raters and the actual values (LCC, pc = 0.70 and 0.84 without and with the SADs, respectively). The reliability of estimates was improved (ICC = 0.54 and 0.82 without and with the SADs, respectively). The effect of rater location on overall concordance was significant without and with the SADs based on an analysis of variance (ANOVA) using a general linear model and lsmeans separation (P<0.05). A generalized linear mixed model analysis revealed that there was a significant interaction between rater location, experience, and the use of the SADs, with some raters having greater improvement in generalized bias and concordance. Raters had a significantly better accuracy when rating 'small' leaves (LCC, pc = 0.86) compared to 'large' leaves (LCC, pc = 0.82) when using the SADs, highlighting the impact of psychophysics on field evaluations of plant disease severity. The proposed SADs will serve as an improved tool for performing pecan leaflet scab assessments by the pecan research community.

Accuracy of Visual Estimation of Blood Loss among Healthcare Providers : A Cross-Sectional Comparative Study

Accuracy of Visual Estimation of Blood Loss among Healthcare Providers : A Cross-Sectional Comparative Study

Visual estimation of shoulder posture: accuracy and reliability across five planes of motion

Background: Visual estimation is still widely used by physiotherapists in clinical practice. The accuracy and reliability of visual estimation are under question and vary with the joint being evaluated. The utility of using visual estimation to evaluate shoulder angular posture is inconclusive and has yet to be evaluated across a comprehensive range of planes and postures.Objective: The purpose of this observational, cross-sectional study was to determine whether visual estimation is an accurate and reliable procedure for determining shoulder angular postures in a range of shoulder motions.Methods: Sixty-three physical therapy students viewed digital photographs of an asymptomatic volunteer to visually estimate degrees of arm abduction, flexion, extension, internal rotation, and external rotation. Six photographs from each plane of movement were shown, at positions spanning the available range of motion, and participants were asked to estimate the angular posture. Estimates were averaged, and errors from computer measurements were calculated. Differences between estimates and measurements were determined with t-tests.Results: The overall accuracy of the visual estimates is considered poor to fair. Root mean square errors were reasonable, from 5° to 17°, but the 95% spread of the data reached a maximum of 53°. Estimates were most accurate at the abduction and flexion postures closest to 90°. Most estimates for extension were underestimated, while more internal rotation estimates were overestimated. Reliability ranged from poor to fair (0.12–0.63).Conclusions: Using visual estimation to evaluate shoulder planar postures results in a wide range of error. Physiotherapy students should be encouraged to use more objective measurement methods.

Accuracy of visual estimation of blood loss in pregnancy by using simulated case scenarios

Introduction Major obstetric haemorrhage continues to be one of the life threatening problems in pregnancy around the world as it accounts for 31% of overall maternal deaths. Objective This observational study is to determine discrepancy between actual blood loss (ABL) and estimated blood loss (EBL). Methods Twelve simulated case scenarios with known measured amounts of blood were created using expired packed red cell and common surgical materials, and assessed by the participants incluing doctors, medical students, nurses and midwives at the Teaching Hospital, Kandy Results There were 120 participants. 30% doctors with 66.7% nurses with mean years of clinical experience at 14.25 years (mode = 5years) and experience to maternity unit at 6.54 years (mode – 5y). Visual estimations were especially inaccurate with smaller volumes, which could be overestimated by up to 120%: surgical towel soaked with 40mL of blood (+75%) and soaked with 60mL of blood(+33%), surgical swab soaked with 15mL of blood(+33%), surgical gauze 18 inch with 100mL of blood(+120%). Blood in a container was more accurately estimated: 300mL of blood in a kidney tray(0%), 500mL of blood in a bowl(0%) Significant underestimation of the ABL occurred in 3 of the 12 stations: blood spill on the floor of 500ml(-20%),1000mL(-40%), 2000mL (-25%). There was no significant differences in clinical experiences and type of exposure in most stations. Conclusion Health care providers tend to overestimate at lower blood volumes ( 500 ml). Further training and monitoring in visual estimation skills are necessary in order to prevent associated maternal mortality and morbidity.

Visual estimation of pro-supination angle is superior to wrist or elbow angles

Objective. To examine our hypothesis that the accuracy of visual estimation, while measuring the angles of forearm, wrist and elbow, may vary between the different angles, and that this may depend on the experience of the observer. Methods. A slide show comprising of clinical photos and radiographs of different elbow, forearm and wrist angles was presented to 164 attending orthopedic surgeons, orthopedic residents and medical students who made a visual estimation of the different joints’ angles. Results. Forearm pronation was found to be estimated most accurately (mean 6.1°) while radiographs of wrist flexion (mean 12°) and photos of wrist extension (mean 16°) were estimated the least accurately. Specialists estimated angles more accurately than residents and both were more accurate than students, regardless of the estimated joint. Conclusions. The accuracy of visual estimation of a joint’s angle depends on the specific joint viewed. Experience in the practice of orthopedic surgery (and not only upper extremity surgery) will improve the accuracy of estimation in general. Regarding the elbow, forearm and wrist, the results of our study suggest that a goniometer should be used whenever an accuracy of up to 10° is important, and for measuring wrist flexion and extension.

Accuracy of visual estimation of the rigidity of a bouncing object

Accuracy of visual estimation of the rigidity of a bouncing object

Accuracy of visual estimation in classifying effort during a lifting task

The objective was to determine if visual estimation of effort (VEE) during lifting tasks is accurate in classifying relative levels of exertion or distinguishing between incomplete lifts that may be potentially unsafe and incomplete lifts of "actors" feigning weakness. A convenience sample of 117 health professionals and lay subjects participated in the study. Four actors were videoed performing four complete dynamic lifts (sets of five repetitions) of varying levels of exertion (relative to subjects' physical maximum). Subjects viewed the videoed performances, presented in no apparent order, attempting to properly classify the lifting tasks. For the four levels of exertion, participants were to judge if the lifts were 25%, 50%, 75% and 100% of each actor's maximum lifting capacity and to distinguish between an incomplete (failed) lift of 110% of maximum and a feigned failure of a lift of 25% of maximum. Accuracy for in classifying all lifting activities was marginally higher than chance. There were no differences in the accuracy of health professionals or lay subjects. The VEE does not accurately classify relative levels of exertion or distinguish between incomplete feigned effort lifts and lifts that are potentially too heavy to safely lift.

Comparison of Methods of Measuring Active Cervical Range of Motion

Experimental study. Cervical range of motion (CROM) was measured using different clinical methods. To compare the reliability and accuracy of visual estimation, tape measurement, and the universal goniometer (UG) with that of the CROM goniometer in measuring active CROM in healthy volunteers. The secondary objective was to identify the single neck movement that best represents overall range of motion. Neck movement is affected by pathology in the spine and shoulder. A reliable and accurate measurement of neck movement is required to quantify injury, recovery, and disability. Various methods of measuring neck movement have been described of which radiography remains the accepted reference standard. However, radiography is impractical for routine clinical assessment. Visual estimation, tape measurement, and the UG are convenient alternatives. To date, the accuracy and reliability of these methods have not been compared in healthy subjects, and the single neck movement that best reflects overall range has not yet been identified. Active cervical flexion, extension, right and left lateral flexion and rotation were measured in 100 healthy volunteers. Visual estimation, tape measurement between fixed landmarks, and the UG aligned on fixed and anatomic landmarks were compared with the CROM goniometer, which was used as the reference standard. Compared with the CROM goniometer, the UG aligned on fixed landmarks was the most accurate method, followed by the UG on anatomic landmarks. The reliability of the UG was between substantial and perfect. Visual estimation was reproducible but measured range of movement inaccurately. Tape measurement was inaccurate. Extension best reflected overall range. The UG aligned on a fixed landmark is most reliable method of measuring neck movement clinically. Where range must be quickly assessed, extension should be measured.

Elaboração e validação de escala diagramática para quantificação da mancha de isariopsis da videira

A falta de um método-padrão de quantificação visual para doenças foliares pode levar a estimativas imprecisas da severidade destas, provocando conclusões erradas. O objetivo deste trabalho foi desenvolver uma escala diagramática para avaliação da mancha de isariopsis em videira causada por Isariopsis clavispora. Uma escala diagramática com seis níveis (1,60; 3,20; 6,60; 13,00; 24,10 e 40,24%) foi desenvolvida e validada para quantificar a severidade da mancha de isariopsis em videira. A validação da escala foi realizada por oito avaliadores, que estimaram a severidade de 30 folhas com diferentes intensidades de doença. Por meio de regressão linear, confrontando valores de severidade reais e estimados, foram analisadas a acurácia e a precisão dos avaliadores que utilizaram a escala diagramática. Foram constadas acurácia e precisão das estimativas visuais efetuadas com o auxílio da escala diagramática. O coeficiente de determinação das regressões foi em média superior a 0,89, e os erros absolutos foram concentrados dentro de limites aceitáveis. Os níveis de acurácia, precisão e reprodutibilidade das mensurações da severidade da mancha de isariopsis da videira melhoraram com o uso da escala diagramática. A escala proposta mostrou-se adequada para avaliação da severidade da mancha de isariopsis da videira.

Observer accuracy and reproducibility of visual estimation of blood loss in obstetrics: how accurate and consistent are health-care professionals?

To evaluate the observer accuracy and intra-observer test-retest reliability of visual estimation of blood loss by midwives and obstetricians. This was a prospective, single-blinded observational study conducted at a London teaching hospital. The accuracy of visually estimating five maternity pads that had been soaked with 25, 50, 100, 150 and 200 ml of blood was assessed. The reproducibility in estimating the same volume (two sets of pads soaked with 50, 100, 150 and 200 ml of blood randomly placed at separate stations) was evaluated by asking participants to visually estimate these volumes. Although there is a tendency to overestimate, the mean percentage difference (estimated-actual volumes) was not significantly different among consultants, trainees and midwives. Visual estimations were especially inaccurate with smaller volumes, which could be overestimated by up to 540%. Test-retest reliability was poor for the larger volumes but statistically acceptable for the smaller volumes, although the difference between the two estimates of the same volume could be as much as 300%. Visual estimations were inaccurate by health-care professionals who have a tendency to overestimate. Experience did not appear to have a confounding effect on accuracy. Further training in visual assessment skills is necessary in order to improve the clinicians' estimation.

Accuracy of Visual Estimates of Damage by the Wheat Stem Sawfly1

Relationships between actual and visually estimated percentages of stems of spring wheat cut by Cephus cinctus Norton in 4 succeeding years were examined. Visual estimates were usually accurate enough to rank varieties of wheat in their proper order according to percentages of stem cut, but they did not provide accurate estimates of the percentages of stems cut or of differences in resistance to sawfly between varieties or replicates. Discrimination changed in the various parts of the continuum. It was best at the mid-level, where, however, the greatest variability in estimation occurred. The percentages of stems cut were usually underestimated. Underestimation is a common feature of visual estimates of other biological categories. The trend for the change in bias of estimation from negative to positive in different parts of the continuum of percentage of sawfly damage followed a similar trend apparent in a test involving estimates of percentages of black peas.

Accuracy of Visual Estimation of Azimuth Position

Accuracy of Visual Estimation of Azimuth Position