Kendall's Tau-c Research Articles

A comparison and normality test of some measures of association via simulation for rectangular doubly ordered cross tables

Spearman and Pearson correlation coefficient, Gamma coefficient, Kendall's tau-b, Kendall's tau-c, and Somers’d are the most commonly used measures of association for doubly either square or rectangular ordered contingency tables. So far, there has been no existing study expressing a formal priority on those measures of association. The aim of this study is not only to compare these measures of association for several types and different sample sizes of generated rectangular (or non-squared) doubly ordered contingency tables and determine which measures of association are more efficient, but also, to check whether each test statistics of ordinal measure of associations satisfies normality assumption under the null hypothesis of independence. Meanwhile, this study deals with the empirical errors of the test statistics under the null hypothesis of independence in order to investigate if the α nominal level is achieved for 12 different rectangular table dimensions and 8 different sample sizes. It is found that both the sample sizes and the dimension of the doubly rectangular ordered contingency tables have a significant effect on these ordinal measures of association. Key words: Measures of ordinal association, rectangular doubly ordered contingency table.

Comparison of the most commonly used measures of association for doubly ordered square contingency tables via simulation

Spearman and Pearson correlation coefficient, Gamma coefficient, Kendall's tau-b, Kendall's tau-c, and Somers' d are the most commonly used measures of association for doubly ordered contingency tables. So far there has been no study expressing a priority on those measures of association. The aim of this study is to compare those measures of association for several types and different sample sizes of generated squared doubly ordered contingency tables and determine which measures of association are more efficient. It is found that both the sample sizes and the dimension of the doubly ordered contingency tables play a significant role on the effect of those measures of association.

Analysis of the expression profile of Dickkopf-1 gene in human glioma and the association with tumor malignancy

BackgroundGliomas represent the most common primary malignant brain tumors, yet little is known about the molecular pathogenesis of these tumors. The highly-regulated Wnt signal transduction pathway is essential for normal developmental processes, and defects in the pathway are closely linked to oncogenesis. Dickkopf-1 (DKK-1) is a secreted protein that acts as a potent inhibitor of the Wnt pathway. The aim of this study was to examine the expression profile of DKK-1 gene in human glioma and its association with tumor malignancy.MethodsWe determined the expression levels of DKK-1 transcript and protein in 12 glioblastoma cell lines, medulloblastoma cells, low-grade glioma cells, and human astrocyte cells by semiquantitative RT-PCR and ELISA. A total of 47 tumor biopsy specimens and 11 normal brain tissue samples from patients with cerebral trauma internal decompression were embedded in paraffin blocks and used for immunostaining. Twenty-six primary tumors and 7 corresponding brain samples were stored in liquid nitrogen and used for RT-PCR. We further examined serologic concentrations and cerebral fluid levels of DKK-1 in patients with tumors.ResultsDKK-1 could only be detected in 12 human glioblastoma cell lines, not in a panel of other tumor and normal cell lines. The difference between glioma patients and healthy individuals was significant. Kendall's tau-c association analysis also revealed the increased DKK-1 protein expression in tumor tissues of higher pathologic classification. The levels of cerebral fluid DKK-1 protein were significantly higher in glioma patients than in healthy donors or in neuronal benign tumor patients, suggesting that the DKK-1 molecule in cerebral fluids can be applicable to detect the presence of glioma and be developed as a novel prognostic treatment.ConclusionThe Wnt antagonist DKK-1 gene may have important roles in glioma tumorigenesis and act as a novel biomarker in human malignant glioblastoma.

Hungarian Roma Attitudes on Minority Rights: The Symbolic Violence of Ethnic Identification

Since 1989 Hungary has undergone profound political and economic changes. The political changes are referred to as ‘democratisation’, a term describing a general shift from an authoritarian to a pl...

An Analysis of the Determinants of Maternal Mortality in Sub-Saharan Africa

To establish what population characteristics affect the high maternal mortality rate in the sub-Saharan Africa region and to propose possible solutions to reduce this rate. This study is a secondary analysis of existing data sources from the World Bank, the World Health Organization (WHO), as well as direct and indirect sources from UNAIDS, the United Nations, Demographic and Health Surveys (DHS), Macro International, and national statistical offices. Instead of looking at continentwide or individual nation models, it develops a regional model. Sociodemographic population variables are used as independent variables to predict the dependent variable, maternal mortality. Additionally, a new country-specific political stability independent variable is introduced into the model. Data from 28 sub-Saharan African countries are used. Bivariate correlations are used to establish associations among the variables, whereas cross-tabulations, using Kendall's tau-c values, and regression lines are used to establish impacts. In the sub-Saharan Africa region, births attended by skilled health personnel and life expectancy at birth strongly correlate with maternal mortality. Gross national product (GNP) per capita and health expenditure per capita also have strong association with maternal mortality. The availability of skilled delivery personnel, life expectancy, national economic wealth, and health expenditure per capita predict the maternal mortality rate of a country. Based on these findings, it is recommended that structural arrangements be made to train skilled health personnel to take care of maternal health problems. In view of the high cost of training physicians, middle-level health personnel may offer an affordable alternative to handle emergency obstetrical cases to address the shortage of physicians. In addition, the allocation of adequate resources to the health sector could improve maternal mortality. The economic wealth of a country and life expectancy at birth are less modifiable through short-term specific interventions. Additionally, it is recommended that country-specific interventions are needed to correct the problem of lack of critical data for analysis.

Incorporating problem-based learning into an obstetrics/gynecology clerkship: impact on student satisfaction and grades

Objective The purpose of this study was to describe the effect of the problem-based learning method on student grade and on student and faculty satisfaction. Study design The problem-based learning method was instituted at 2 of 5 obstetrics/gynecology clerkship sites. Students and faculty were surveyed, with the use of a Likert scale, regarding aspects of satisfaction with the clerkship. Responses were compared according to problem-based learning usage. Student performance was also assessed according to problem-based learning usage, with a comparison of several grade components. Statistical analysis involved t-tests and Kendall's tau-C. Results For the year that was assessed, 54 of 156 students used the problem-based learning method. Mean student satisfaction responses were significantly higher for students who used the problem-based learning method. Faculty satisfaction was also significantly higher for the problem-based learning method, compared with other teaching methods. Mean scores on the National Board of Medical Examiners subject examination were higher for problem-based learning but did not reach statistical significance. Grade distribution was not significantly different for the groups. Conclusion The problem-based learning method was associated with improved student and faculty satisfaction and did not affect student grades negatively.

Incorporating problem-based learning into an obstetrics/gynecology clerkship: impact on student satisfaction and grades*1

<h2>Abstract</h2><h3>Objective</h3> The purpose of this study was to describe the effect of the problem-based learning method on student grade and on student and faculty satisfaction. <h3>Study design</h3> The problem-based learning method was instituted at 2 of 5 obstetrics/gynecology clerkship sites. Students and faculty were surveyed, with the use of a Likert scale, regarding aspects of satisfaction with the clerkship. Responses were compared according to problem-based learning usage. Student performance was also assessed according to problem-based learning usage, with a comparison of several grade components. Statistical analysis involved <i>t</i>-tests and Kendall's tau-C. <h3>Results</h3> For the year that was assessed, 54 of 156 students used the problem-based learning method. Mean student satisfaction responses were significantly higher for students who used the problem-based learning method. Faculty satisfaction was also significantly higher for the problem-based learning method, compared with other teaching methods. Mean scores on the National Board of Medical Examiners subject examination were higher for problem-based learning but did not reach statistical significance. Grade distribution was not significantly different for the groups. <h3>Conclusion</h3> The problem-based learning method was associated with improved student and faculty satisfaction and did not affect student grades negatively.

Venture Capitalists' Screening Criteria

Indian venture capital industry is one of the predominant players among South Asian countries. New funds have opened their shop here and are continuing to bring in more funds. The industry has undergone a major shift in focus. India is not a country which offers lower-cost production alternatives but is a high-tech and global outsourcing centre. The present study reports four factors which are used by the venture capitalists to screen new venture proposals. Using Kendall's tau-c analysis, the study brings out strong association between several variable pairs. Broadly, the analysis finds that: Successful venture teams put in sustained efforts on identified target markets. They are highly meticulous while attending to the details. These teams are adept at dealing with risk because of their impeccable past experience. Indian venture capitalists do not seem to be much enamoured of technology venturing; at least some of the successful ventures funded by them do not seem to show signs of being hi-tech. The study brings out four important variables which are highly unique to successful venture in India. They are: ability to evaluate and react to risk attention to details market share profits. Evaluating risk seems to be an area where unsuccessful ventures fail. Since successful teams focus on established markets and meticulously pursue these markets to gain market share, they achieve desired profits. The future research may explore the process of screening and evaluation by investigating the same through other means such as qualitative technique and techniques from cognitive psychology. The aspect of accuracy of venture capitalists' introspection would be an interesting area to study. Unless more research is conducted in the cognitive process of venture capitalists' decision-making, our understanding would remain insufficient.

Asthma Severity, Psychiatric Morbidity, and Quality of Life: Correlation with Inhaled Corticosteroid Dose

Objectives. Psychiatric phenomena in asthma has been debated for some time. Inhaled corticosteroids (ICS) are a significant part of treatment. We attempted to quantify the prevalence of psychiatric morbidity relative to asthma severity, quality of life (QOL), and ICS dose. Data Sources. Fifty asthmatic patients (18 ≥ X ≤ 75 years) on ICS, attending an urban clinic had asthma and ICS dose stratified by symptom severity and preparation potency. Peak flow and forced expiratory volume in 1 second (FEV1) were measured. Patients completed general QOL and disease-specific QOL questionnaires, along with psychiatric rating scales. Results. Patients (n = 50) clustered in the 40–59 year range (n = 27, 54%) and were predominantly female (n = 44, 88%) Hispanics (n = 30, 60%), with mild-moderate asthma (n = 18, 36%) and on low-dose ICS (n = 22, 44%). FEV1 ranged from 32 to 123 (mean 76.98, SE 3.01). Peak flow ranged from 210 to 590 (mean 407.83, SE 13.24). Prevalence of anxiety and depressive symptoms were higher than expected (Kendall's tau-c, n = 50, P < .01). Independently, high ICS dose and asthma severity correlated directly with all measures of psychiatric morbidity (Pearson's r 0.781, P < .01). High ICS dose correlated inversely with SF-36 Mental Component Scale (Pearson's r 0.681, P < .01) and directly with FEV1 and peak flow when age/sex adjusted (Spearman's rho: 0.660, P < .001). Conclusions. Psychiatric morbidity is more prevalent in this population and impacts negatively on QOL. Use of high-dose ICS benefited pulmonary function and “physical” QOL, yet may have negatively affected patients' mental well-being. Longitudinal follow-up, extension of sample size, and better study control would allow closer approximation of possible negative associations with ICS.

PHYSICAL FUNCTION TESTING OF ELDERLY SUBJECTS: ASSOCIATION WITH SELF-REPORTED ACTIVITY AND HEALTH PERCEPTION 603

Physical function is thought to be important to maintain health and independence in later life. Balance, gait, strength, endurance and flexibility were evaluated in a community setting for 461 elderly subjects (mean age 75, range 66-95) who also completed a PA questionnaire and a Short Form 36 (SF-36) general health questionnaire. Of these subjects, 303 were offered regular supervised physical activities within their own community or home. Repeat SF-36s were completed at 1 year into the PA intervention. Poorer health perception was associated with lower PA scores and poorer scores on physical performance tests (Spearman). Greater scores on self reported physical activity were associated with better physical function (Kendall's Tau-c). Reported physical activity declined steadily with age for females but remained about the same for males. Performance on the functional tests of chair rise, grip strength, endurance walk, shoulder flexibility and 8-foot walk declined steadily with age for both males and females. Those who participated in at least 1 exercise session/week reported significant improvement in the dimensions of general health, vitality and physical role. This study provides evidence that simple field-based physical function measures can be used to categorize older persons and that physical function is related to self-reported health. Furthermore, the provision of community based physical activities for older people leads to significant improvement in self-reported health for regular attenders.

Spatial and Temporal Changes in Subtidal Benthic Crustaceans Along a Coastal River-Estuarine Gradient in Mississippi

Benthic crustaceans were collected monthly between 24 August 1985 and 20 September 1986 from tidal freshwater (TFW), oligohaline (OH) and mesohaline (h4H) sites in Old Fort Bayou, a black-water tidal river of the Biloxi Bay estuary, Mississippi. Salinity varied seasonally and spatially and was primarily related to variations in rainfall during this study. Reduced rainfall after October 1985 resulted in the upstream movement of saline water and a concommitant shift in benthic crustaceans upstream with this change in the physical-chemical environment. This shift is supported by a significant positive concordance of ranks between salinity and relative abundance of Gammarus sp. A (Kendall's tau-c = 0.458 and Spearman's rs = 0.704, p<0.007) and G. mucromatus (Kendall's tau-c = 0.497 and Spearman's r, = 0.701, p <0.007) at TFW indicating that when salinity became high, so did the relative abundance of these two species in TFW. No specimens of either species were collected at this site during the same months in 1985. There was no relationship between salinity and relative abundance of G. bonnieroides (Kendall's tau-c = 0.201 and Spearman's rs = 0.381, p = 199) in the TFW site. At the OH site, there was a marginally significant concordance (Kendall's tau+ = 0.432 and Spearman's rp = 0.545, p = .053) between salinity and relative abundance of G. bonnieroides but not for the other two species. Riverine estuarines are by nature dynamic in their physicalchemical environment. Such variation influences macrobenthic distribution which has important trophic implications because these organisms form a large portion of the food base for higher trophic levels, such as fishes.

Multiple Correlation and Ordinally Scaled Data

Four alternative measures of multiple correlation for ordinally scaled data are discussed: Goodman and Kruskal's gammiiiia, Somers' d,x, Kendall's tau-c, and a new measure, ganima-k. They differ in their assumptions about the circumstances in which predictions should be evaluated, and also in their properties. Gammt1la and d,x may both decrease in value, implying a reduction in predictability, with the introduction of an additional predictor. By contrast, taui-c and gamma1w-k do not fall in value. S ince Goodman and Kruskal (1954) defined nonparametric association in terms of the reduction in erroneous predictions, their measure of correlation for ordinally scaled data, ay, has proved useful in many contexts. It is defined, in their notation, as

Does Methodology Affect the Students’ Perceived Level of English Proficiency? A case Study

The present study delves into the perceptions and opinions of first year university students regarding their experiences in the teaching-learning process of a second language dur-ing secondary education. Accordingly, the paper details a cross-sectional study carried out with a sample of 1,729 students of the Faculty of Social Sciences and Law of Rey Juan Carlos University in Madrid. The variables related to the methodology used by the teachers, exposure to the target language, classroom activities and learning resources come under consideration as the factors that influence the students’ linguistic competence in English. We used a questionnaire to collect the data from the participants and a Likert scale to measure the variables concerning the methodology used in the teaching of a foreign language. In order to study the possible correlations and their intensity of independence, Kendall Tau-b, Kendall Tau-c and Gamma contrasts were conducted, using the Statistical Package for the Social Sciences (SPSS) 25.0. The findings suggest a signi-ficant positive correlation between the students’ perceived level of English proficiency, classroom activities and the methodology used. The study revealed that the students’ perceived level of pro-ficiency in spoken English was average, although they indicated that their level should have been higher in light of the number of years spent studying it.

Ego States of nurses working in psychiatric clinics according to transactional analysis theory.

Objective:An effective interpersonal communication is an essential nursing skill required to help provide quality health care and meet the treatment objectives. The aim of this study was to investigate the communication between the psychiatric nurses and the patients in terms of Transactional Analysis Theory ego states.Methods:The quantitative and qualitative research methods were used. The descriptive statistics (frequency, percentage, mean, standard deviation) were used in the data analysis and Kendall’s Tau-c coefficient was used to assess the agreement among the observers.Results:Of the psychiatric nurses, 66.7% (n = 14) had served as a psychiatric nurse for 1-10 years. Among the nurses, 52.4% (n=11) had received training about communication from any institution/organization. The agreement among the opinions of the nurses, the researcher and the charge nurses about the psychiatric nurses’ ego states showed that there was a significant relationship between the researcher’s opinion of the nurses’ ego states and the charge nurses’ opinion of the nurses’ ego states in terms of Critical Parent, Nurturing Parent, Adult, Adapted Child and Natural Child ego states.Conclusion:It is suggested that training be offered in regards to raising awareness about ulterior transactions that can affect communication negatively, patient autonomy and therapeutic communication in particular, and patients requiring the use of special communication methods.