Kendall's “Tau” Coefficient as an Index of Similarity in Comparisons of Plant or Animal Communities

1963 ◽  
Vol 95 (6) ◽  
pp. 568-575 ◽  
Author(s):  
A. W. Ghent
Keyword(s):  
Soil Fauna ◽  
Rank Correlation ◽  
Special Problem ◽  
The Other ◽  
Confidence Limits ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
Animal Communities ◽  
Graph Form ◽  
Zero Frequency

AbstractComparisons of ecologic communities are often limited to presentations of frequency lists in tabular or bar-graph form. Kendall's “Tau” coefficient is appropriate as a measure of rank correlation between such numerical profiles. A special problem arises where species in one community are absent from the other. Such species may either be assigned zero frequency and last-place ranking in the community where they are absent, or they may be dropped from both rankings, depending on which method yields the more conservative correlation. Tau has the same limits (± 1) as the familiar product-moment correlation coefficient. Moreover, as a nonparametric statistic it is free of considerations of distribution. Comparisons between soil-fauna communities from the Quetico-Superior forest area are used to illustrate the method. The problems of tied rankings, variance and significance of Tau, confidence limits for Tau, and the significance of a difference between Tau coefficients, are also considered.

scholarly journals Automatic Evaluation of Information Ordering: Kendall's Tau

2006 ◽  
Vol 32 (4) ◽  
pp. 471-484 ◽  
Author(s):  
Mirella Lapata
Keyword(s):  
Evaluation Method ◽  
Rank Correlation ◽  
Automatic Evaluation ◽  
Text Generation ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
Kendall’S Τ ◽  
Multidocument Summarization

This article considers the automatic evaluation of information ordering, a task underlying many text-based applications such as concept-to-text generation and multidocument summarization. We propose an evaluation method based on Kendall's τ, a metric of rank correlation. The method is inexpensive, robust, and representation independent. We show that Kendall's τ correlates reliably with human ratings and reading times.

scholarly journals Correlation Test Application of Supplier’s Ranking Using TOPSIS and AHP-TOPSIS Method

CAUCHY ◽  
2016 ◽  
Vol 4 (2) ◽  
pp. 65 ◽  
Author(s):  
Ika Yuniwati
Keyword(s):  
Ordinal Data ◽  
Selection Process ◽  
Rank Correlation ◽  
P Value ◽  
Topsis Method ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
Spearman Rank ◽  
Correlation Test ◽  
Spearman’S Rank Correlation

The supplier selection process can be done using multi-criteria decision making (MCDM) methods in firms. There are many MCDM Methods, but firms must choose the method suitable with the firm condition. Company A has analyzed supplier’s ranking using TOPSIS method. TOPSIS method has a marjor weakness in its subjective weighting. This flaw is overcome using AHP method weighting having undergone a consistency test. In this study, the comparison of supplier’s ranking using TOPSIS and AHP-TOPSIS method used correlation test. The aim of this paper is to determine different result from two methods. Data in suppliers’ ranking is ordinal data, so this process used Spearman’s rank and Kendall’s tau b correlation. If most of the ranked scored are same, Kendall’s tau b correlation should be used. The other way, Spearman rank should be used. The result of this study is that most of the ranked scored are different, so the process used Spearman rank p-value of Spearman’s rank correlation of 0.505. It is greater than 0.05, means there is no statistically significant correlation between two methods. Furthermore, increment or decrement of supplier’s ranking in one method is not significantly related to the increment or decrement of supplier’s ranking in the second method

Do Adult Disease Severity Subclassifications Predict Use of Cyclophosphamide in Children with ANCA-associated Vasculitis? An Analysis of ARChiVe Study Treatment Decisions

2012 ◽  
Vol 39 (10) ◽  
pp. 2012-2020 ◽  
Author(s):  
KIMBERLY MORISHITA ◽  
JAIME GUZMAN ◽  
PETER CHIRA ◽  
EYAL MUSCAL ◽  
ANDREW ZEFT ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pediatric Patients ◽  
Severe Disease ◽  
Rank Correlation ◽  
Antineutrophil Cytoplasmic Antibody ◽  
Chi Square ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
Adult Disease ◽  
Choice Of Treatment

Objective.To determine whether adult disease severity subclassification systems for antineutrophil cytoplasmic antibody-associated vasculitis (AAV) are concordant with the decision to treat pediatric patients with cyclophosphamide (CYC).Methods.We applied the European Vasculitis Study (EUVAS) and Wegener’s Granulomatosis Etanercept Trial (WGET) disease severity subclassification systems to pediatric patients with AAV in A Registry for Childhood Vasculitis (ARChiVe). Modifications were made to the EUVAS and WGET systems to enable their application to this cohort of children. Treatment was categorized into 2 groups, “cyclophosphamide” and “no cyclophosphamide.” Pearson’s chi-square and Kendall’s rank correlation coefficient statistical analyses were used to determine the relationship between disease severity subgroup and treatment at the time of diagnosis.Results.In total, 125 children with AAV were studied. Severity subgroup was associated with treatment group in both the EUVAS (chi-square 45.14, p < 0.001, Kendall’s tau-b 0.601, p < 0.001) and WGET (chi-square 59.33, p < 0.001, Kendall’s tau-b 0.689, p < 0.001) systems; however, 7 children classified by both systems as having less severe disease received CYC, and 6 children classified as having severe disease by both systems did not receive CYC.Conclusion.In this pediatric AAV cohort, the EUVAS and WGET adult severity subclassification systems had strong correlation with physician choice of treatment. However, a proportion of patients received treatment that was not concordant with their assigned severity subclass.

A Comparison of Computed Tomography Scans and Digital Periapical Radiographs Ridge Height Measurements

2015 ◽  
Vol 41 (2) ◽  
pp. 125-131
Author(s):  
Ravichandra Juluri ◽  
Maria Moran ◽  
Jon B. Suzuki ◽  
Ahmed Khocht
Keyword(s):  
Rank Correlation ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
High Positive Correlation ◽  
Imaging Methods ◽  
Digital Radiographs ◽  
Kendall Rank Correlation ◽  
Ridge Height ◽  
Inferior Alveolar Canal ◽  
Absolute Agreement

To investigate the agreement between computerized tomography scans (CT) and intraoral periapical digital radiographs (PA) alveolar ridge height measurements in maxillary and mandibular posterior regions. We reviewed 100 implant patient radiographic records and identified 27 mandibular sites in 19 patients and 23 maxillary sites in 13 patients with available CT scans and matching PA radiographs. The distance from the crest of the ridge to the floor of the maxillary sinus or to the superior border of the inferior alveolar canal was measured. PAs were measured with Dexis software v. 8.0 and CTs were measured with Simplant software v. 11.02. Two examiners (RJ and MM) recorded the measurements separately; each examiner recorded two readings. The average of the 4 readings was used for data analysis. Absolute agreement: Paired t test comparing ridge-height measurements between the two imaging methods showed no differences for maxillary sites (P &gt; 0.2) and significant differences for the mandibular sites (CT &gt; PA, P = 0.0009). Relative agreement: Kendall rank correlation analysis of ridge-height measurements between the 2 imaging methods showed a high positive correlation for maxillary sites (Kendall's tau = 0.76, P = 0.0001) and moderate correlation for the mandibular sites (Kendall's tau = 0.46, P = 0.001). Maxillary PAs tend to approximate CT ridge-height measurements. By contrast mandibular PAs tend to underestimate the distance from the crest of the ridge to the inferior alveolar canal.

scholarly journals Corrected Evolutive Kendall’s τ Coefficients for Incomplete Rankings with Ties: Application to Case of Spotify Lists

Mathematics ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1828
Author(s):  
Francisco Pedroche ◽  
J. Alberto Conejero
Keyword(s):  
Group Decision ◽  
Industrial Applications ◽  
The Other ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
On Demand ◽  
Wide Range ◽  
Kendall’S Τ ◽  
Internet Streaming ◽  
Grant Proposals

Mathematical analysis of rankings is essential for a wide range of scientific, public, and industrial applications (e.g., group decision-making, organizational methods, R&D sponsorship, recommender systems, voter systems, sports competitions, grant proposals rankings, web searchers, Internet streaming-on-demand media providers, etc.). Recently, some methods for incomplete aggregate rankings (rankings in which not all the elements are ranked) with ties, based on the classic Kendall’s tau coefficient, have been presented. We are interested in ordinal rankings (that is, we can order the elements to be the first, the second, etc.) allowing ties between the elements (e.g., two elements may be in the first position). We extend a previous coefficient for comparing a series of complete rankings with ties to two new coefficients for comparing a series of incomplete rankings with ties. We make use of the newest definitions of Kendall’s tau extensions. We also offer a theoretical result to interpret these coefficients in terms of the type of interactions that the elements of two consecutive rankings may show (e.g., they preserve their positions, cross their positions, and they are tied in one ranking but untied in the other ranking, etc.). We give some small examples to illustrate all the newly presented parameters and coefficients. We also apply our coefficients to compare some series of Spotify charts, both Top 200 and Viral 50, showing the applicability and utility of the proposed measures.

scholarly journals Pituitary Deformation in High Altitude Immigrants and the Correlation with Headache：A Preliminary Study.

2021 ◽  
Author(s):  
Jie Feng ◽  
Xiao Yu ◽  
Weiwei Men ◽  
Wenjia Liu ◽  
Shiyu Zhang ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
High Altitude ◽  
Brain Mri ◽  
Rank Correlation ◽  
Categorical Variables ◽  
Intracranial Volume ◽  
Continuous Variables ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
Objective Indicator

Abstract Aim: To investigate pituitary gland deformation (PGD) in high altitude (HA) immigrants and determine if a correlation exists between PGD with headache and the ratio of brain volume to total intracranial volume (BV/TIV), and to investigate whether PGD can be used as an objective indicator of headache in HA immigrants.Methods: A total of 34 male HA immigrants and 60 age- and gender-matched sea-level (SL) residents were enrolled in this study. 3D T1 weighted brain MRI scans and headache scales were acquired. HA participants were classified into headache positive (HA[+]) and headache negative (HA[-]) subgroups. PGD was graded visually on mid-sagittal images of the pituitary gland. All continuous variables and categorical variables were compared using Student's t-test or Mann-Whitney test and the χ2 or Fisher exact tests, respectively. Kendall's tau rank correlation coefficient and Spearman’s rho were used to investigate the relationship between PGD and headache or BV/TIV, respectively. Receiver operating characteristic (ROC) analysis was used to evaluate whether PGD can be used as an objective indicator of headache in HA immigrants.Results: A higher proportion of HA participants had PGD (54.8%) than SL residents (23.3%) (p=0.005). The proportion of HA(-) participants with PGD (68.2%) was higher than that of HA(+) participants (22.2%) (p=0.044). PGD was negatively correlated with headache (Kendall's tau=-0.323, p=0.0097) and positively correlated with BV/TIV (r=0.454, p=0.010). The presence of PGD was an indicator of headache in HA immigrants (area under the ROC curve=0.712, p= 0.038, sensitivity=0.778, specificity=0.682). Conclusion: A greater proportion of HA immigrants had PGD, which is an adaptation to chronically altered ICP or compliance. The presence of PGD indicated a restoration of spatial compensatory capacity and compliance of intracranial system, leading to headache relief. PGD is a potential indicator of headache in HA immigrants.

scholarly journals Workload for radiologists during on-call hours: dramatic increase in the past 15 years

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
R. J. M. Bruls ◽  
R. M. Kwee
Keyword(s):  
Western Europe ◽  
Kendall Test ◽  
Kendall’S Tau ◽  
Kendall's Tau ◽  
X Ray ◽  
The Past ◽  
Relative Value ◽  
Burn Out ◽  
Picture Archiving And Communication ◽  
Ct Studies

Abstract Background The objective of this study is to investigate the workload for radiologists during on-call hours and to quantify the 15-year trend in a large general hospital in Western Europe. Methods Data regarding the number of X-ray, ultrasound and computed tomography (CT) studies during on-call hours (weekdays between 6.00 p.m. and 7.00 a.m., weekends, and national holidays) between 2006 and 2020 were extracted from the picture archiving and communication system. All studies were converted into relative value units (RVUs) to estimate the on-call workload. The Mann–Kendall test was performed to assess the temporal trend. Results The total RVUs during on-call hours showed a significant increase between 2006 and 2020 (Kendall's tau-b = 0.657, p = 0.001). The overall workload in terms of RVUs during on-call hours has quadrupled. The number of X-ray studies significantly decreased (Kendall's tau-b = − 0.433, p = 0.026), whereas the number of CT studies significantly increased (Kendall's tau-b = 0.875, p < 0.001) between 2006 and 2020. CT studies which increased by more than 500% between 2006 and 2020 are CT for head trauma, brain CTA, brain CTV, chest CT (for suspected pulmonary embolism), spinal CT, neck CT, pelvic CT, and CT for suspected aortic dissection. The number of ultrasound studies did not change significantly (Kendall's tau-b = 0.202, p = 0.298). Conclusions The workload for radiologists during on-call hours increased dramatically in the past 15 years. The growing amount of CT studies is responsible for this increase. Radiologist and technician workforce should be matched to this ongoing increasing trend to avoid potential burn-out and to maintain quality and safety of radiological care.

A study of in-patients aged 60 years and over treated in the Department of Plastic Surgery, Dundee Royal Infirmary, in 1983

1985 ◽  
Vol 71 (3) ◽  
pp. 171-175
Author(s):  
C. D. T. Low
Keyword(s):  
Health Service ◽  
Elderly Patients ◽  
Plastic Surgery ◽  
Special Problem ◽  
The Other ◽  
Special Consideration ◽  
Direct Result ◽  
Royal Infirmary ◽  
Delayed Healing ◽  
Available Resources

SummaryThis study was conducted to determine the extent to which elderly patients constitute a special problem in plastic surgery. In 1983 patients aged 60 years and over accounted for 3 7% of all admissions to the plastic surgery ward at the Dundee Royal Infirmary and 52% of all patient-days there; they tended to stay longer than other patients and cost the Health Service more than £130000. About one-third of admissions were as a direct result of accidents; of the other two-thirds, the majority was for the treatment of malignancies. In the study, special consideration was given to delayed healing after surgery and other problems arising while these patients were in hospital, and the reasons for prolonged stays. The study confirms that there is a problem which is stretching available resources.

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