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Results for “correlation matrix”

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PubMed2003

Multivariate analysis of sexual dimorphism in two types of dermatoglyphic traits in five endogamous populations of West Bengal, India.

Five different endogamous populations who encompass the main social rank in the caste hierarchy of West Bengal were analysed for this report. The present approach is to compare the pattern of sex differences/similarities exhibited by two different sets of dermatoglyphic traits. Cluster and discriminant analysis and Mantel test of matrix correlations were performed. The nature of variation between sexes within population groups and two types of variable sets has a good similarity in all five populations. These results strongly suggest that the two categories of dermatoglyphic variables provide similar possibilities to discriminate between the sexes in populations.

Adult↗

PubMed2002

Oral health of 12-year-old Bangladeshi children.

Previous dental caries studies in Bangladesh have been performed on non-randomized samples, using various clinical criteria. Estimates of dental caries prevalence in 12-year-olds are therefore uncertain. In the present study a clustered, stratified random sampling procedure was used. Dental caries was stored as DMFT in accordance with the WHO recommendations and related to oral hygiene and various behavioral and social variables. The caries experience was found to be low, with a mean DMFT score of experience was 0.97. Poor oral hygiene and bleeding gingiva were frequently detected. Dental caries associated with sex, oral hygiene (girls), and use of dental services (more caries among frequent users than non-users). A Correlation matrix analyzing the most influential independent variables indicated that sex and oral hygiene seemed to have an independent effect, whereas a web of social factors interfered with the use of dental services' variable.

Analysis of Variance↗

PubMedDate not supplied

Evidence for a deployment-related Gulf War syndrome by factor analysis.

To identify a syndrome unique to Gulf War veterans, the authors applied an exploratory factor analysis to the 47-symptom correlation matrix of 10,423 Gulf War and 8,960 non-Gulf War veteran respondents. A separate factor analysis was performed for Gulf War and non-Gulf War veterans, and the resulting 6 factors were compared between the 2 groups. Five of the factors were very similar in the 2 groups; however, 1 of the factors in the Gulf War group, but not the non-Gulf War group, contained a cluster of symptoms consistent with neurological impairment. Symptoms specific to this factor were blurred vision, loss of balance/dizziness, tremors/shaking, and speech difficulty. The Gulf War veterans who had all of the aforementioned symptoms (n = 277) also reported exposures to several putative risk factors at a rate 3 or more times higher than other Gulf War veterans. This finding suggests a possible syndrome related to Gulf War deployment, which requires objective supporting clinical evidence.

Adult↗

PubMed2001

Age-related changes in fear, sociality and pecking behaviours in two strains of laying hen.

1. Two lines of commercial hybrid layers (Tetra and ISA Brown) were reared from hatch to 30 weeks of age in groups of 8. The objectives of the experiment were to evaluate the significance of the different selection practices involved in the development of the lines and to assess the potential association between selected behavioural states and the potential for feather damage and cannibalism. 2. Behavioural tests related to fear (tonic immobility, novel object, open field), sociality (runway, proximity in the home pen) and pecking (feather bunch and focal observations of inter-bird and environmental pecking) were conducted at 0 to 2, 5 to 7, 12 to 14, 19 to 21 and 29 to 31 weeks of age. Scan sampling of general behaviour was also conducted at these ages. 3. Underlying sociality was greater in Tetras than in ISA Brown hens. 4. There were no apparent overall strain differences in fearfulness although ISA Brown hens showed significantly longer tonic immobility fear reactions than Tetras at 31 weeks of age. 5. ISA Brown hens gave and received more gentle pecks than Tetra hens whereas preening was commoner among Tetras. There were no strain differences in the number of pecks at litter or food. 6. As birds aged they showed less avoidance of novel objects and Tetras, though not ISA Browns, showed progressively shorter tonic immobility responses. Birds of both strains spent less time resting, more foraging (pecking and scratching) and pecked more at the feather bunch at older ages. 7. Measures taken in the TI, open field, runway (social affiliation) and feather bunch tests were stable over time whereas focal observations of pecking at hens and the environment were not. 8. Factor Analysis showed that 3 factors defined by the novel object test, environmental pecking and pecking ata feather bunch explained most of the variation in the correlation matrix between summary measures for the 8 behavioural traits.

Age Factors↗

PubMedDate not supplied

The use of the Circadian Type Inventory as a measure of the circadian constructs of vigour and rigidity.

The Circadian Type Inventory (Folkard 1987) was administered to 191 students (150 females and 41 males). Corrected item to total correlations for both the Vigour and Rigidity scales were low to moderate. The internal reliabilities of the scales indicate that Vigour is statistically more homogeneous (0.74) than Rigidity (0.58). In the absence of the original CTI correlation matrix, replication using a 2-factor principal component varimax solution was undertaken. It explained only 26.7% of the variance. Post hoc factor analyses yielded 3 factors which explained 33.4% of the variance. The relatively low amounts of variance explained and the inadequate transfer of the circadian constructs of Rigidity and Vigour into question items does not recommend the use of the CTI to measure circadian rhythm characteristics in order to predict tolerance to shiftwork.

Adolescent↗

PubMed1992

Nature of romantic love in female adolescents.

In the present study, I intended to determine the similarity between Rubin's (1970) Love Scale components and five of Lee's (1976) six lovestyles in a relatively homogenous sample of 301 16- and 17-year-old British females. Items describing loving behaviors toward a particular individual were formulated to measure these lovestyles together with that of Ludus. The six orthogonal factors extracted from the correlation matrix of these and Rubin's items were called Love, Mutual Love, Respect, Similarity, Physical Attraction and Hostility. The results suggested that Rubin's Love Scale contained elements of Mania and Agape but none of Ludus, which could not be further differentiated. Rubin's (1970) Liking Scale, however, could be further subdivided into Respect (Pragma) and Similarity (Storge).

Adolescent↗

PubMedDate not supplied

Investigation of trace element content of cheese.

Nine trace elements (Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd, Pb) were determined in cheese by atomic absorption spectrophotometry with electrothermal atomization in a graphite tube, using the ashing procedure. Associations among mineral constituents were studied by means of principal component analysis, which allows determination of interdependences among trace elements in foods. A test for normality was used to investigate monovariate distributions, in order to estimate the symmetry of data vector. The correlation matrix was used as a starting matrix for principal component analysis; nine variables were reduced to four principal components. The clusters of elements appear to be determined by their origin.

Cheese↗

PubMedDate not supplied

Interrelationships among certain measures of growth and maturation rate in boys during adolescence.

Relationships among ages at attaining 17 or 21 indices of maturity were considered in a longitudinal sample of 177 Polish boys examined at annual intervals from 1961 to 1972. Maturity indicators included ages at peak velocity for stature, sitting height, leg length and weight; ages at attaining 80%, 90%, 95% and 99% of adult stature; ages at attaining the median skeletal maturity scores (TW-2) characteristic of chronological ages 11, 12, 13, 14, and 15 years; and ages at attaining stages II and IV of genital and public hair development. Age at initiation of the stature spurt (take-off) and ages at eruption of 14, 20 and 26 permanent teeth were ascertained for only 111 boys. All intercorrelations among the developmental indicators were positive. Ordering the correlation matrix gave three clusters: (1) a large central group including age at take-off and ages at all peak velocities, at genital and pubic hair stages II and IV, at attaining 90%, 95% and 99% of adult stature, and at the later stages of skeletal maturity; (2) indices of the tempo of maturation during prepubertal and/or early pubertal stages; and (3) ages at attaining a given number of permanent teeth. Results of a principal components analysis of the ages indicated two principal components, the first accounting for about 77% of the sample variance and the second for about 12%. The first principal component is apparently a general maturity factor, while the second apparently relates to the rate of skeletal maturity during pre-adolescence.

Adolescent↗

PubMedDate not supplied

Influence of religion and birthplace on the genetic structure of Northern Ireland.

The effect of geographic and religious subdivision on the genetic structure of Northern Ireland was assessed using data on 10 craniofacial measurements collected on 755 adult males that were born in five counties and belonged to one of three religious affiliations (Catholic, Church of Ireland, Presbyterian). Fifteen samples were defined based on birth county and religious affiliation. Two-way univariate and multivariate analysis of variance shows significant effects of birth county and religious affiliation, with somewhat greater subdivision due to religion. Distance matrix correlations reveal a small, but significant, effect of birth county and religious affiliation on the pattern of genetic distances between the 15 samples, with a slightly greater influence of religion. The Church of Ireland samples show the greatest differences. perhaps revealing the combined influence of differential population origins and religious differences as a barrier to gene flow. Overall, religion has a significant, though minor, influence on genetic variation in Northern Ireland.

Adult↗

PubMed1986

Evaluation of silica gel cartridges coated in situ with acidified 2,4-dinitrophenylhydrazine for sampling aldehydes and ketones in air.

A procedure for coating in situ silica gel in prepacked cartridges with 2,4-dinitrophenylhydrazine (DNPH) acidified with hydrochloric acid is described. The coated cartridge was compared with a validated DNPH impinger method for sampling organic carbonyl compounds (aldehydes and ketones) in diluted automotive exhaust emissions and in ambient air for subsequent analysis of the DNPH derivatives by high performance liquid chromatography. Qualitative and quantitative data are presented that show that the two sampling devices are equivalent. The coated cartridge is ideal for long-term sampling of carbonyls at sub to low parts-per-billion level in ambient air or for short-term sampling of carbonyls at low ppb to parts-per-million level in diluted automotive exhaust emissions. An unknown degradation product of acrolein has been tentatively identified as x-acrolein. The disappearance of acrolein in the analytical sample matrix correlates quantitatively almost on a mole for mole basis with the growth of x-acrolein. The sum of the concentration of acrolein and x-acrolein appears to be invariant with time.

Air Pollutants↗

PubMed2006

Performance tolerance and boat set-up in elite sprint kayaking.

The aim of this study was to examine the inter-relationship between athlete morphology, equipment set-up and performance in elite sprint kayaking. Correlations applied to data from the 2000 Olympics were used to select the most important links between morphology and boat set-up--paddle grip width and foot-bar distance. Associations between body size and the above selected equipment set-ups were calculated using a Pearson correlation matrix, to facilitate the logical selection of independent variables as input for regression analyses. Significant (p < 0.01) regression equations were developed for the prediction of foot-bar distance (r2 = 0.589: standard error of estimate (SEE) = 4.48) and paddle grip width (r2 = 0.541: SEE = 3.08). Three national-standard sprint kayakers used their preferred set-up together with modifications of their predicted set-up, derived from Olympic data, to test performance tolerance in sprint kayaking. Mean coefficients of multiple determination over three trials for the three paddlers of 0.91, 0.91 and 0.92 for left paddle force, right paddle force, and paddle angle at water entry, respectively, were recorded when using their preferred set-up. These data showed that the paddlers produce consistent patterns of motion. The intervention of altering the boat set-up resulted in varying changes to boat speed. The mean preferred speed for the three paddlers of 4.47 m/s was reduced by 0.07 and 0.10 m/s when the above boat set-up was modified to a predicted and 'predicted plus one standard deviation'respectively. These changes in boat speed were the result of alterations in the mechanics of paddling technique.

Adult↗

PubMed1999

Sample size for comparing linear growth curves.

Assuming a linear growth curve model under a suitable link function, we compute the sample size for comparing two treatment groups when the repeated measurements marginally follow exponential family distributions. From the treatment profiles of the chosen link function, we compute the common intercept beta0 and the regression slopes beta1 and beta2 to define delta = beta1 - beta2, the difference to be detected, under a specified alternative hypothesis. The dispersion matrices of the generalized estimating equations estimators are obtained under the null and alternative hypotheses using a suitable working correlation matrix. We compute the sample size assuming that delta is asymptotically normal. Details are worked out for repeated measures designs with binary and count data along with numerical examples.

Female↗

PubMed1999

Methicillin-resistant Staphylococcus aureus and antimicrobial use in Belgian hospitals.

OBJECTIVE: To investigate relationships between the incidence of methicillin-resistant Staphylococcus aureus (MRSA) and the use of different classes of antimicrobials in Belgian hospitals. DESIGN: Using Pearson correlation coefficients, the number of new nosocomial MRSA-colonized or -infected patients in the second half of 1994 and the first half of 1995 reported by the national MRSA surveillance program was compared with use of various antimicrobial classes as reported by the National Institute for Sickness and Disability Insurance. Relationships between different classes of antimicrobials were evaluated in a correlation matrix. MRSA incidence, antimicrobial use, and potential confounding factors were included in a multiple linear regression analysis. SETTING: 50 hospitals in Belgium. RESULTS: The use of a number of different classes of antimicrobials was interrelated. In the multivariate analysis, the incidence of nosocomial MRSA increased with increasing use of ceftazidime and cefsulodin (P=.0003), amoxicillin with clavulanic acid (P=.02), and quinolones (P=.005). No association was found between MRSA incidence and total antimicrobial use. CONCLUSIONS: The relationships between antimicrobial use and MRSA are complex. Interventions aimed at promoting more rational prescribing patterns should be supported by adequate experimental and epidemiological evidence. Advice for preventing and controlling MRSA has focused mainly on hygienic measures and precautions to avoid cross-transmission; the role of relieving antimicrobial pressure needs to be clarified.

Anti-Bacterial Agents↗

PubMed1996

Search of periodicities in primary structure of biopolymers: a general Fourier approach.

We discuss a new convenient way to study periodical patterns in primary structures of biopolymers which appeared recently. For the sequence of a biopolymer the symbolic correlation function is constructed, which is used as a digital sequence thus allowing us to perform a Fourier transform. Another fruitful technical improvement is the closing of the sequence in the ring with further scanning of the ring length, which allows the study of periods of the order of the sequence length. This approach makes it possible to take into account any scores describing similarity between symbols and to compare results obtained using different Fourier-like and correlation matrix techniques. An algorithm to compute Fourier spectrum power allows detection of vague periods in sequences containing strong repeats. A PASCAL program, SYMFOUR, has been written and tested on both sequences with periodical patterns, already reported, and sequences and other sites interesting from a biological point of view.

Algorithms↗

PubMed1984

Factor analysis as a tool in community diagnosis.

For the family physician, community diagnosis can be likened to individual diagnosis by the application of methods of information acquisition and analysis. This paper describes the technique of factor analysis, applied to data from an urban inner-city area, for reducing a multitude of factors to a manageable number without an appreciable loss of information. The variables were selected from four broad categories which have been shown to influence both health states and health care needs: demography, socioeconomics, social disorganization and morbidity/mortality. A correlation matrix based on 40 of the most accessible indices served as input for a principal axes factor analysis. Six factors accounted for 74% of the total variance and were interpreted as: 'Poverty and social disorganization', 'Distribution and problems of the elderly', 'Ethnic composition', 'Fertility', 'Infant mortality' and 'Foetal mortality'. Representative indices from each factor were then mapped to identify and display census tract differences. Finally, the application of the factors to a specific community illustrated important differences within the community and identified areas of high risk and need.

Factor Analysis, Statistical↗

PubMed2003

Further evaluation of the basic nature of the human biological aging process based on a factor analysis of age-related physiological variables.

This study aimed to reexamine whether there exists a primary aging process that controls the rate of aging in a number of different functions. Eighty-six adult males who successively received a 2-day routine health checkup test for 7 years from 1992 to 1998 at the Kyoto Red Cross Hospital were selected as subjects. Nine candidate biomarkers of aging were selected from the 25 physiological variables based on the investigation of age-related changes. A principal factor analysis was applied to the partial correlation matrix for 9 selected biomarkers calculated by controlling for age. Furthermore, a confirmatory factor analysis in testing first- and second-order factor models was applied to the covariance matrix for 9 biomarkers. The results of these factor analyses revealed that there existed one general factor and three system-specific factors. Therefore, biological age changes can be viewed as a time-dependent complex integration of the primary and secondary aging processes.

Adult↗

PubMed1978

Principles for identifying structural differences. Some methodological issues related to comparative factor analysis.

Several recent articles published in the Journal of Gerontology have been concerned with changes in factor structure of various psychological, social, and medical fitness measures. The present article reviews four principles for comparing structures and evaluates several recent articles in terms of these principles. The four principles are concerned with resolving: (1) problems of metric, (2) problems of rotation to similarity, (3) the number of factors problem, and (4) problems related to different extraction or rotational procedures across comparison groups. Utilization of a different metric in each correlation matrix implies that results may be a simple artifact of a different metric for each group. Failure to rotate to similarity and insufficient care with regard to the number of factors problem may result in artificially dissimilar structures. Finally, in comparing results across studies, differences in extraction or rotational procedures across different studies may result in differing results as artifacts of the methods employed.

Factor Analysis, Statistical↗

PubMed2006

The influence of maternal lineages on social affiliations among humpback whales (Megaptera novaeangliae) on their feeding grounds in the southern gulf of Maine.

Humpback whales on their feeding grounds in the Gulf of Maine typically form fluid fission/fusion groups of two to three individuals characterized by noncompetitive and, at times, cooperative behavior. Here we test the hypothesis that, despite the apparent absence of close kinship bonds, the fluid associations between feeding whales are influenced by "maternal lineages" as represented by mtDNA haplotypes. Using skin samples collected with a biopsy dart, variation in the hypervariable segment of the mtDNA control region identified 17 unique haplotypes among 159 individually identified whales from the southern Gulf of Maine. The haplotypes of a further 143 individuals were inferred from known direct maternal (cow-calf) relationships. The frequencies of associations among these 302 individuals were calculated from 21,617 sighting records collected from 1980 to 1995, excluding associations between a cow and her dependent calf. For groups of two where the haplotypes of both individuals were known (n = 3,151), individuals with the same haplotype were together significantly more often (26%) than expected by random association (20%). To account for different group sizes and associations with individuals of unknown haplotype and sex, we used Monte Carlo simulations to test for nonrandom associations in the full data set, as well as known female-only (n = 1,512), male-only (n = 730), and mixed-sex (n = 2,745) groups. Within-haplotype associations were significantly more frequent than expected at random for all groups (P = .002) and female-only groups (P = .011) but not male-only groups, while mixed-sex groups approached significance (P = .062). A Mantel test of individual pairwise association indices and haplotype identity confirmed that within-haplotype associations were more frequent than expected for all sex combinations except male-male associations, with females forming within-haplotype associations 1.7 times more often than expected by random assortment. Partial matrix correlations and permutation analyses indicated that the skew toward within-haplotype associations could not be accounted for by short-term temporal co-occurrence or fine-scale spatial distributions of individuals with shared haplotypes. While the mechanism by which individuals with a common mtDNA haplotype assort remains unknown, our results strongly suggest an influence of maternal lineages on the social organization of humpback whales within a regional feeding ground.

Animals↗