Clustering stocks using partial correlation coefficients

2016 ◽  
Vol 462 ◽  
pp. 410-420 ◽  
Author(s):  
Sean S. Jung ◽  
Woojin Chang
Keyword(s):  
Partial Correlation ◽  
Correlation Coefficients

scholarly journals The First National Survey of Cadmium in Cacao Farm Soil in Colombia

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 761
Author(s):  
Daniel Bravo ◽  
Clara Leon-Moreno ◽  
Carlos Alberto Martínez ◽  
Viviana Marcela Varón-Ramírez ◽  
Gustavo Alfonso Araujo-Carrillo ◽  
...  
Keyword(s):  
Graphical Models ◽  
Partial Correlation ◽  
National Level ◽  
Prediction Method ◽  
Correlation Coefficients ◽  
Predictive Performance ◽  
Nationwide Survey ◽  
Critical Discussion ◽  
Cadmium Content ◽  
Soil Variables

This study represents the first nationwide survey regarding the distribution of Cd content in cacao-growing soils in Colombia. The soil Cd distribution was analyzed using a cold/hotspots model. Moreover, both descriptive and predictive analytical tools were used to assess the key factors regulating the Cd concentration, considering Cd content and eight soil variables in the cacao systems. A critical discussion was performed in four main cacao-growing districts. Our results suggest that the performance of a model using all the variables will always be superior to the one using Zn alone. The analyzed variables featured an appropriate predictive performance, nonetheless, that performance has to be improved to develop a prediction method that might be used nationwide. Results from the fitted graphical models showed that the largest associations (as measured by the partial correlation coefficients) were those between Cd and Zn. Ca had the second-largest partial correlation with Cd and its predictive performance ranked second. Interestingly, it was found that there was a high variability in the factors correlated with Cd in cacao growing soils at a national level. Therefore, this study constitutes a baseline for the forthcoming studies in the country and should be reinforced with an analysis of cadmium content in cacao beans.

SERUM GONADOTROPHINS, TESTOSTERONE AND SPERMATOGENESIS IN SUBFERTILE MEN

1977 ◽  
Vol 86 (3) ◽  
pp. 651-658 ◽  
Author(s):  
J. H. Aafjes ◽  
J. C. M. van der Vijver ◽  
R. Docter ◽  
P. E. Schenck
Keyword(s):  
Partial Correlation ◽  
Sperm Count ◽  
Correlation Coefficients ◽  
Serum Levels ◽  
Significant Negative Correlation ◽  
The Other ◽  
Sperm Production ◽  
Positive Correlation ◽  
Natural Logarithm ◽  
Biopsy Score

ABSTRACT In 210 subfertile men there existed a significant positive correlation between serum FSH and LH (0.41). No correlation was observed between the gonadotrophin levels and testosterone. In contrast to this FSH as well as LH were negatively correlated with the natural logarithm (In) of the sperm count/ml ejaculate (−0.44 and −0.18, respectively). When the positive correlation which existed between FSH and LH was used to calculate partial correlation coefficients, the coefficient between FSH and ln sperm count did hardly change (−0.41) the coefficient between LH and ln sperm count on the other hand became insignificant (−0.05). This suggests that spermatogenesis influences FSH serum levels in subfertile men by a decreased suppression when sperm production is diminished. Testicular biopsies taken from 97 of these patients were used to determine biopsy scores. These scores showed a significant negative correlation with FSH (−0.34) and a positive one with ln sperm count/ml ejaculate (0.45). Interestingly the biopsy score of 16 patients who fertilized their wives, was found to be higher compared with the score of the other patients who did not fertilize. The number of sperm/ml ejaculate and the FSH values of these 2 groups of biopsied patients were, however, not significantly different. This leads to the conclusion that the biopsy score is a better parameter for the evaluation of oligospermic men than either sperm count or FSH serum values.

scholarly journals Pre-service Science and Mathematics Teachers’ Teaching Efficacy Beliefs and Attitudes toward Teaching: A Partial Correlation Research

2020 ◽  
Vol 45 (9) ◽  
pp. 42-61
Author(s):  
Busra Kartal ◽  
Keyword(s):  
Mathematics Teachers ◽  
Elementary Science ◽  
Partial Correlation ◽  
Correlation Coefficients ◽  
Efficacy Beliefs ◽  
Positive Attitudes ◽  
And Mathematics ◽  
High Level ◽  
Science And Mathematics Teachers ◽  
Beliefs And Attitudes

Teachers with a high level of self-efficacy and positive attitudes are more likely to use new and constructivist approaches and to create a learning environment in which students may develop 21st-century skills. Examining pre-service teachers’ attitudes and beliefs related to teaching allow teacher preparation programs to evaluate their effectiveness on beliefs and attitudes. This correlational research investigated pre-service elementary science and mathematics teachers’ beliefs and attitudes due to gender, grade level, and department, and revealed the reliable correlation between beliefs and attitudes performing partial correlation. Results show that females feel more efficacious in teaching and have more positive attitudes than males. 4th grades also perceive a higher level of efficacy for student engagement and using instructional strategies than 1st grades. Partial correlation coefficients revealed positive strong relationships between attitudes and efficacy beliefs. Recommendations are suggested based on implications.

GROWTH AND DEVELOPMENT OF PERUVIAN CHILDREN

PEDIATRICS ◽  
1956 ◽  
Vol 17 (4) ◽  
pp. 510-523
Author(s):  
M. F. Trulson ◽  
C. Collazos ◽  
D. M. Hegsted
Keyword(s):  
Rural Areas ◽  
Growth And Development ◽  
Partial Correlation ◽  
Correlation Coefficients ◽  
Significant Degree ◽  
Skeletal Age ◽  
Developmental Patterns ◽  
Specific Effects ◽  
Developmental Age ◽  
Highly Correlated

One hundred nine school children from 2 rural areas in the coastal area of Peru were measured and weighed and roentgenograms of the hand and wrist were obtained. Three-fourths of the children were below Stuart's tenth percentile in height. Roughly, a third of the children were below the tenth percentile in weight. Fifteen per cent of the girls and 30 per cent of the boys were above the fiftieth percentile in weight. Forty to forty-five per cent of the children were in the stocky to obese channels of the Wetzel grid; 5 to 10 per cent would be classified as fair to poor, and roughly half would be considered average. Developmental age (Wetzel) was 7.5 ± 15.6 months less than chronological age for boys, 10.5 ± 11.3 months less for girls. A third of the boys and 15 per cent of the girls were advanced in Wetzel developmental age. It was apparent that the heavier children were generally advanced in Wetzel developmental age. Roentgenograms of the hand and wrist were assessed by comparing the films to the Greulich-Pyle Standards. Skeletal age was -11.3 ± 12.7 months for boys and -7.1 ± 9.8 for girls. Eighteen per cent of the population were advanced in skeletal age. Boys were more retarded than girls in skeletal age. The correlation and partial correlation coefficients for all combinations of the 4 measurements (retardation in weight, retardation in height, retardation in skeletal age and retardation in developmental age) were calculated. The various pairs were all rather highly correlated, this being particularly true of weight and Wetzel developmental age. The partial correlation coefficients show, however, that skeletal age was not closely correlated with any of the other 3 measurements. Height and developmental age were negatively correlated to a significant degree, and developmental age and weight were so closely related that they appear to be measures of the same characteristic in this population. Individual dietary histories are not available from these children, but it is known that the diets in the area are considerably below recommended levels in certain nutriients. Whether dietary deficiencies are factors in the apparently abnormal developmental patterns, or if the patterns are truly abnormal for the Peruvian child or indicate an adverse effect on health, remain to be shown. It is pointed out that there are probably advantages in studies upon growth and development in different areas of the world where a variety of dietary or environmental factors may have specific effects.

Correlation of Neuropsychiatric Symptoms in Dementia with Brain Perfusion: A 99mTc-SPECT-HMPAO Study with Brodmann Areas Analysis

2021 ◽  
Vol 19 ◽  
Author(s):  
Varvara Valotassiou ◽  
Nikolaos Sifakis ◽  
Chara Tzavara ◽  
Evi Lykou ◽  
Niki Tsinia ◽  
...  
Keyword(s):  
Partial Correlation ◽  
Motor Behavior ◽  
Neuropsychiatric Symptoms ◽  
Correlation Coefficients ◽  
Principal Component ◽  
Lewy Body Dementia ◽  
Brain Perfusion ◽  
Neuropsychiatric Inventory ◽  
Different Types ◽  
Brodmann Areas

Background: Neuropsychiatric symptoms (NPSs) are common in dementia. Their evaluation is based on Neuropsychiatric Inventory (NPI). Neuroimaging studies have tried to elucidate the underlying neural circuits either in isolated NPSs or in specific forms of dementia. Objective: : The objective of this study is to evaluate the correlation of NPS in the NPI with Brodmann areas (BAs) perfusion, for revealing BAs involved in the pathogenesis of NPSs in dementia of various etiologies. Method: We studied 201 patients (82 with Alzheimer's disease, 75 with Frontotemporal dementia, 27 with Corticobasal Syndrome, 17 with Parkinson Disease/Lewy Body Dementia). Exploratory factor analysis was carried out to evaluate underlying groups of BAs, and Principal Component analysis was chosen as extraction method using Varimax rotation. Partial correlation coefficients were computed to explore the association of factors obtained from analysis and NPI items controlling for age, educational yeas, and ACE-R. Results: We found 6 BAs Factors(F); F1 (BAs 8,9,10,11,24,32,44,45,46,47, bilaterally), F2 (Bas 4,5,6,7,23,31, bilaterally), F3 (BAs 19,21,22,37,39,40, bilaterally), F4 (BAs 20,28,36,38, bilaterally), F5 (BAs 25, bilaterally) and F6 (BAs 17,18, bilaterally). Significant and negative correlation was found between NPI1 (delusions) and F3,F6, NPI2 (hallucinations) and F6, NPI7 (apathy) and F1,F4,F5, NPI3 (agitation) - NPI10 (aberrant motor behavior) - NPI12 (eating disorders) and F1. We did not find any significant correlation for NPI4,5,6,8,9,11 (depression, anxiety, euphoria, disinhibition, irritability, sleep disorders, respectively). Conclusion: Several NPSs share the same BAs among different types of dementia, while the manifestation of the rest may be attributed to different neural networks. These findings may have an impact on patients’ treatment.

scholarly journals Computing the Partial Correlation of ICA Models for Non-Gaussian Graph Signal Processing

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 22 ◽  
Author(s):  
Jordi Belda ◽  
Luis Vergara ◽  
Gonzalo Safont ◽  
Addisson Salazar
Keyword(s):  
Signal Processing ◽  
Partial Correlation ◽  
Correlation Coefficients ◽  
Real Data ◽  
Linear Estimation ◽  
Precision Matrix ◽  
Conditional Mean ◽  
Graph Signal Processing ◽  
Gaussian Case ◽  
Non Gaussian

Conventional partial correlation coefficients (PCC) were extended to the non-Gaussian case, in particular to independent component analysis (ICA) models of the observed multivariate samples. Thus, the usual methods that define the pairwise connections of a graph from the precision matrix were correspondingly extended. The basic concept involved replacing the implicit linear estimation of conventional PCC with a nonlinear estimation (conditional mean) assuming ICA. Thus, it is better eliminated the correlation between a given pair of nodes induced by the rest of nodes, and hence the specific connectivity weights can be better estimated. Some synthetic and real data examples illustrate the approach in a graph signal processing context.

Use of element-mineral correlations to investigate fractionation of rare earth elements in fine-grained sediments

1994 ◽  
Vol 58 (393) ◽  
pp. 533-541 ◽  
Author(s):  
J. T. Temple ◽  
J. N. Walsh
Keyword(s):  
Rare Earth ◽  
Correlation Analysis ◽  
Rare Earth Elements ◽  
Partial Correlation ◽  
Correlation Coefficients ◽  
Partial Correlation Analysis ◽  
Middle Ordovician ◽  
Fine Grained ◽  
South Wales

AbstractRelative concentrations of elements in the minerals of fine-grained sediments can be inferred from element-mineral correlation coefficients. The technique is applied to the distribution of REE in Middle Ordovician shales from South Wales analysed by ICPAES, Leco C/S125 and XRD. Phosphate and chlorite show mid-REE enrichment; muscovite + biotite shows mid-REE depletion. The complementarity of the chlorite and muscovite + biotite patterns may be due to fractionation during diagenetic recrystallisation. Partial correlation analysis is used to infer the presence of zircon.

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