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PubMedDate not supplied

A conversational program for hierarchic and non-hierarchic cluster analysis.

The theoretical basis and the features of some cluster analysis programs are described in this paper. These programs use as input data an N x M matrix. For the N' less than or equal to N set of individuals, the cross-correlation matrix, R = (rij), is then calculated. The dissimilarity matrix, D = (dhk), and the distribution histogram of the distances between each pair is worked out. Hierarchic and non-hierarchic clustering techniques are allowed. Using the non-hierarchic strategy, the non-overlapping clusters are then separated into different groups. The distances between these groups are calculated and statistical tests of significance are performed. In the hierarchic case, a dendrogram is drawn using an agglomerative algorithm. As an example the programs (written in FORTRAN, batch or TSS version) were used to classify human mitotic chromosomes.

Classification↗

PubMedDate not supplied

Psychological, behavioral, and family characteristics of pediatric patients with chronic pain: a 1-year retrospective study and cluster analysis.

OBJECTIVES: There has been a longstanding recognition that adult patients with chronic pain are not a homogenous population and that there are subgroups of patients who report high levels of distress and interpersonal difficulties as well as subgroups of patients who report little distress and high functioning. The purpose of the present study was to attempt to identify similar subgroups in a pediatric chronic pain population. METHODS: The sample consisted of 117 children with chronic pain and their parents who were assessed in a multidisciplinary pain clinic during 2001. Participants completed a set of psychologic self-report questionnaires, as well as demographic and pain characteristic information. A cluster analysis was conducted to identify 3 distinct subgroups of patients to replicate similar studies of adult chronic pain sufferers. RESULTS: Overall, mean scores were within population norms on measures of distress and family functioning, with somatic symptoms at a level of clinical significance. The cluster analysis identified the 3 subgroups that were strikingly similar to those identified in adult chronic pain populations: one with high levels of distress and disability, another with relatively low scores on distress and disability, and a third group that scored in between the other 2 on these measures but with marked low family cohesion. DISCUSSION: The similarity of these subgroups to the adult chronic pain population subgroups as well as implications for future studies are discussed.

Adolescent↗

PubMed2005

Chemical fingerprinting of Isatis indigotica root by RP-HPLC and hierarchical clustering analysis.

The aim was to establish a method for extraction and chemical fingerprinting of extracts of Isatis indigotica roots ("Ban-Lan-Gen") and to apply the method developed to 18 Ban-Lan-Gen samples. RP-HPLC with gradient elution was performed on authentic reference standards of powdered I. indigotica roots, indigotin and indirubin purchased from the National Institute for the Control of Pharmaceutical and Biological Products (NICPBP) of China. Eighteen "Ban-Lan-Gen" samples (including the reference powdered herb) were bought from Singapore and different regions in China. Comparisons of the chromatograms showed that the samples can be divided into three groups. The chromatograms of the extracts of five samples were found to be similar to that of the extract of the authentic sample. Eight other samples had similar peaks as the authentic sample but the intensities of the peaks were generally lower, except for the peaks between retention times of 10-40 min. Peaks in these regions were more intense than those found in the extract of the authentic sample. Forty-five characteristic peaks could be found in the extracts of all the above samples. Peaks at retention times 52 and 53 min were determined to be indigotin and indirubin, respectively. The remaining four samples had similar chemical fingerprints to each other but were different from that of the authentic sample. Hierarchical clustering analysis gave similar results as the visual comparison. The RP-HPLC method developed allows simple identification and comparisons of I. indigotica roots. This is the first report of hierarchical clustering analysis of I. indigotica root.

Chromatography, High Pressure Liquid↗

PubMed1995

Characterisation of Nile and drinking water quality by chemical and cluster analysis.

Nile- and drinking water samples were collected from several locations between Aswan city and Cairo before and during the flood. Short-time activation analysis was applied to determine the concentrations of Al, Ca, Cl, F, K, Mg, Na and V, while Ba, Cr, Co, Fe, Hf, Rb, Sb, Sc and Zn were determined by irradiating the samples for 20 h at a neutron flux of 1.8 x 10(12) cm-2 s-1. The values of dissolved oxygen, nitrate, sulphate, orthophosphate, organic matter and the pH were determined by applying the standard methods. All data were examined statistically, and classified using cluster analysis technique. The results show that the concentrations of the major and trace elements in drinking water are higher compared with their levels in Nile water. This indicates that the water pumped from the Nile for use as drinking water is mixed with underground water before supplying. It has also been found that the concentrations of nitrate and phosphate in Nile water are significantly higher in Aswan than in those taken from the lower parts of the Nile. Cluster analysis proved to be an ideal technique for classifying these types of samples according to their sampling time and sites.

Cluster Analysis↗

PubMed1997

Academic goals and emotions: results of a structural equation model and a cluster analysis.

BACKGROUND: Motivational researchers have suggested that the environment plays a key role in students' goal formation. However, some recent work (Seifert, 1996) suggests that students' emotions may play a role in goal formation. AIM: This study examined the relationship between environment, emotions, and goals. Do emotions and perceptions of teachers both contribute to goal orientation, or do emotions mediate the influence of perceptions of teachers on goal orientation? SAMPLE: 559 Grade 10 students in Newfoundland and Labrador. METHOD: Two structural equations were postulated: one in which students' affect mediated the influence of perceptions of teachers on goal orientation and one in which students' affect contributed to goal formation in addition to perceptions of teachers. A cluster analysis of affect scores was performed followed by between-group and within-group contrasts of goal orientation scores. RESULTS: The structural equation model in which emotions mediate the influence of perceptions of teachers on goal orientation fit the data better than the model in which perceptions of teachers directly predicted goal orientation. The cluster analysis showed that groups with different profiles of affect pursued different goals. CONCLUSIONS: Emotions seem to be directly linked to goal orientation. Teachers who are perceived as nurturing will foster feelings of self-assuredness and control in students which will lead to a learning orientation.

Adolescent↗

PubMed1999

Chronic pain and distress in older people: a cluster analysis.

Chronic pain represents a major health problem among older people. The aims of the present study were to: (i) identify various profiles of pain and distress experiences among older patients; and (ii) compare whether background variables, sense of coherence, functional ability and experiences of interventions aimed at reducing pain and distress varied among the patient profiles. Interviews were carried out with 42 older patients. A cluster analysis yielded three clusters, each representing a different profile of patients. Case illustrations are provided for each profile. There were no differences between the clusters, regarding intensity and duration of pain. One profile, with subjects of advanced age, showed a decreased functional ability and favourable scores in most of the categories of pain and distress. Another profile of patients showed favourable mean scores in all categories. The third cluster of patients showed unfavourable scores in most categories of pain and distress. There appears to be a need to treat the three groups of patients in different ways in the caring situation.

Activities of Daily Living↗

PubMed2005

Attitudes and skills of Hong Kong Chinese medicine practitioners towards computerization in practice: a cluster analysis.

The objective was to determine whether definable subtypes exist within a cohort of Hong Kong Chinese medicine practitioners (CMPs) as related to computer use in their clinical practices based on their skills, attitudes, and background factors. Data were collected using a structured questionnaire. The sample of 954 CMPs was recruited in Hong Kong. The study employs personal and demographic variables, attitudes, and a skills scale. A cluster analysis yielded three clusters. Each cluster represents a different profile of Hong Kong CMPs on computer use in their clinical practices. A clear profile of Hong Kong CMPs may benefit healthcare professionals in appropriate education or assistance to prompt the use of computers by CMPs, an officially recognized profession.

Adult↗

PubMed1986

Heterogeneity of systemic lupus erythematosus elucidated by cluster analysis. The influence of HLA.

For 75 patients with systemic lupus erythematosus (SLE), 39 laboratory and clinical characteristics, including HLA-A, B, C and DR typing, were analysed using a cluster analysis technique. Three groups were identified. Group I (46 patients) was characterized by infrequently severe disease, good response to therapy and infrequent multisystem involvement. Group II (24 patients) was characterized by a severe course of disease (although the tendency to remit after therapy was not unusual), and frequently, renal involvement and pericarditis. Group III (5 patients) was characterized by more severe renal disease. Of the 75 patients studied, 38.7% possessed HLA-DR3, compared to 17.4% of controls. Group I patients did not differ from controls but 80% of Group II patients and 4/5 Group III patients had DR3. Cluster analysis identifies subsets of SLE patients who show marked differences in disease course and severity, correlated with possession of the HLA B8, DR3 phenotype.

HLA Antigens↗

PubMed2006

Investigating nurses' knowledge, attitudes, and skills patterns towards clinical management system: results of a cluster analysis.

To determine whether definable subtypes exist within a cohort of Hong Kong nurses as related to the clinical management system use in their clinical practices based on their knowledge, attitudes, skills, and background factors. Data were collected using a structured questionnaire. The sample of 242 registered nurses was recruited from three hospitals in Hong Kong. The study employs personal and demographic variables, knowledge, attitudes, and skills scale. A cluster analysis yielded two clusters. Each cluster represents a different profile of Hong Kong nurses on the clinical management system use in their clinical practices. The first group (Cluster 1) was labeled 'lower attitudes, less skilful and average knowledge' group, and represented 55.4% of the total respondents. The second group (Cluster 2) was labeled as 'positive attitudes, good knowledge but less skilful'. They comprised almost 44.6% of this nursing sample. Cluster 2 had more older nurses, the majority were educated to the baccalaureate or above level, with more than 10 years working experience, and they held a more senior ranking then Cluster 1. A clear profile of Hong Kong nurses may benefit healthcare professionals in making appropriate education or assistance to prompt the use of the clinical management system by nurses an officially recognized profession. The findings were useful in determining nurse-users' specific needs and their preferences for modification of the clinical management system. Such findings should be used to formulate strategies to encourage nurses to resolve actual problems following computer training and to increase the depth and breadth of nurses' knowledge, attitudes, and skills toward such system.

Adult↗

PubMed1996

Evaluation of HPLC retention data by non-linear mapping, cluster analysis and varimax rotation. A comparative study.

The retention of 17 propargylamine derivatives was determined on a beta-cyclodextrin polymer (beta-CDP)-coated silica column using tetrahydrofuran-0.05 M K2HPO4 (6:4, v/v) as eluent. The inclusion complex formation between the propargylamine derivatives and a water-soluble beta-CDP was studied by charge-transfer chromatography carried out on reversed-phase TLC layers. The capacity factors were correlated with the various measured and calculated physicochemical parameters of the solutes using principal component analysis followed by non-linear mapping, varimax rotation and cluster analysis. Calculations proved that the hydrophobicity and steric parameters have the highest influence on the retention of propargylamine derivatives. It has been established that each statistical method can be used for the evaluation of similar retention data matrices, however, the results can be slightly different according to the method applied.

Chromatography, High Pressure Liquid↗

PubMed1997

The use of cluster analysis for cell typing.

In invertebrates, large neurons, identifiable in each animal, have proven to be useful models for investigating basic neurobiological phenomena. In vertebrates, the number of neurons and the complexity of nervous systems increase and 'identifiability' is lost. To compensate for this, other approaches must be adopted to study the vertebrate brain. One successful approach has been to identify cell types, recognizable in each individual. The identification of cell types in central nuclei has helped us understand the organization of these nuclei and has provided an important foundation for examining possible relationships between the structure and function of neurons. Unfortunately, not all nuclei are composed of neurons of readily identifiable types. Nuclei lacking distinct cell types are, in general, less well understood than nuclei with morphologically distinct cell types. This article describes a statistical approach known as cluster analysis that we used to define cell types in the nucleus of the solitary tract-a nucleus that had been suggested to contain identifiable cell types but within which cell typing had proven difficult. Similar techniques have been used to classify Golgi-impregnated cells in the ventrobasal complex of the dog, the subthalamic nucleus of the bushbaby and the human retina. Cluster analysis has also been used in the gustatory system, in general, and nucleus of the solitary tract, in specific, to classify electrophysiologically characterized cells. The method also includes a technique for verifying the utility of the resulting classification.

Animals↗

PubMed2002

Exploring regions of interest with cluster analysis (EROICA) using a spectral peak statistic for selecting and testing the significance of fMRI activation time-series.

Much relevant information about activations and artifacts in a functional magnetic resonance imaging (fMRI) dataset can be obtained from an exploratory cluster analysis. In contrast to testing the significance of the measured experimental effect for a given model, unsupervised pattern recognition techniques, such as fuzzy clustering, often find unexpected behavior in addition to expected activations, allowing the exploitation of this element of surprise. The many artifact clusters often discovered might aid the experimenter in deciding whether the dataset is usable, whether some additional preprocessing step is required, or whether the one used has introduced spurious effects. However, clustering alone does not complete the analysis because the membership values that are generated are not indicative of the level of statistical significance with respect to the cluster activation patterns (centroids). This is of particular importance for fMRI datasets for which most time-series are "noise", with no activation patterns. We propose that an initial partition step should precede the clustering step. Only time-series that meet a certain statistical criterion (using a scaled version of Fisher's g-order statistic) are selected for clustering; this typically represents <5% of the whole brain region. The purpose of clustering is to generate a set of cluster centers that are the possible activation patterns; these are used in forming a linear model of all the time-series. The model parameter is tested for significance in both the time and frequency domains. We present a novel method of conducting these tests, which limits the number of false positives. We call the three-step process of initial partition, clustering and the two-domain significance test as exploring regions of interest with cluster analysis (EROICA).

Brain↗

PubMed2002

Exploration of coping patterns in burned adults: cluster analysis of the coping with burns questionnaire (CBQ).

The aim of this study was to investigate coping patterns, health status and personality traits in burned adults. Subjects were 161 burn patients treated at the Uppsala University Hospital between 1980 and 1995. Measures were the coping with burns questionnaire (CBQ), the burn specific health scale-brief (BSHS-B) and the Swedish universities scales of personality (SSP). The CBQ was subjected to a K-means cluster analysis and three clusters were derived: extensive, adaptive, and avoidant copers. Extensive copers used the most coping and took an intermediate role regarding health status and the personality trait of neuroticism. Adaptive copers preferred the strategies emotional support and optimism/problem solving, and had the highest health status ratings. Avoidant copers preferred the strategy avoidance and reported the lowest use of emotional support and optimism/problem solving. They had the lowest health status ratings and the highest ratings on neuroticism and aggressiveness. The clusters did not differ in severity of injury or time since injury. In conclusion, coping patterns can be discerned among burn patients, and those individuals preferring avoidance and lacking other coping options displayed more maladaptive traits and poorer health status years after the burn.

Adaptation, Psychological↗

PubMed2004

A pilot study on nurses' attitudes toward perinatal bereavement support: a cluster analysis.

AIM: Nurses' attitudes towards perinatal bereavement care are explored by identifying profiles of nurses working in a Hong Kong Obstetrics and Gynaecology (OAG) unit. Relationships between nurses' attitudes towards bereavement support, need for bereavement training and hospital policy are explored. RESEARCH METHOD: 110 nurses recruited from the OAG unit of a large Hong Kong public hospital completed a structured questionnaire. OUTCOME MEASURES: Attitudes towards perinatal bereavement support; required support and training needs for nurses on bereavement care. RESULTS: Two-step cluster analysis yielded two clusters. Cluster A consisted of 55.5% (n = 49) and cluster B consisted of 44.5% (n = 61) of nurses. Cluster A nurses were younger, had less OAG experience, more junior ranking and less education than cluster B nurses. Cluster B nurses had additional midwifery and bereavement care training, personal grieving experiences and experience handling grieving clients. The majority held positive bereavement care attitudes. Significant differences towards perinatal bereavement support were found. Only 25.5% (n = 28) had bereavement related training. Attitudes towards bereavement care were positively correlated with training needs (rs = 0.59) and hospital policy support (rs = 0.60). CONCLUSION: Hong Kong nurses emphasized need for increased bereavement care knowledge and experience, improved communication skills, and greater hospital and team members' support. Findings may be used to improve support of nurses, to ensure sensitive bereavement care in perinatal settings, and to enhance nursing curricula.

Adult↗

PubMed2003

Attitudes of Hong Kong Chinese to traditional Chinese medicine and Western medicine: survey and cluster analysis.

OBJECTIVES: To determine whether within a cohort of Hong Kong out-patients definable subtypes exist based on their attitudes to traditional Chinese medicine and Western medicine. DESIGN: Data were collected using a structured questionnaire. SETTING: The sample of 503 subjects was recruited at two local outpatient clinics in Hong Kong. MAIN OUTCOME MEASURES: The study employs demographic variables, illness status, the Chinese-Western Medical Belief Scale, trust of physicians and subjects' preferences on consultation fees, attitude of health care professional, efficacy of service and waiting time during consultation. RESULTS: A cluster analysis yielded three clusters based on their attitudes towards traditional Chinese and Western medicine. One cluster, 24% of the sample, is noted for being older, poorer, more likely to be female and to have chronic conditions; they are sceptical of western physicians. The second cluster (63% of the sample) is younger and have considerably more belief in Western than traditional Chinese medicine. The third group (14%) is intermediate in age and is noted for a marked faith in both forms of medicine. CONCLUSIONS: A clear profile of these attitudes of Hong Kong Chinese may benefit health care professionals in making appropriate patient-doctor relationships and planning patient care.

Adolescent↗

PubMed1997

Classification of shoulder complaints in general practice by means of cluster analysis.

OBJECTIVE: To determine if a classification of shoulder complaints in general practice can be made with a cluster analysis of variables of medical history and physical examination. METHOD: One hundred one patients with shoulder complaints were examined upon inclusion (week 0) and after 2 weeks. Eleven variables of the medical histories and 19 variables of the physical examinations were used for the analysis. RESULTS: The analyses of week 0 and week 2 reveal three stable clusters: one cluster with almost half of the patients who hardly had limitations in the range of scapulohumeral mobility (ROM), one cluster with a small number of patients with a short history of complaints and a limitation of scapulohumeral mobility in all directions (7 and 6, respectively), and a third cluster containing the rest of the patients, with 30% to 50% limitation in ROM. The degree of limitation in ROM decreased after 2 weeks. Comparison of the patients in the clusters of week 0 and week 2 revealed a shift of patients within the clusters, although the number of patients in the clusters remained almost constant. CONCLUSION: Only three stable clusters could be identified, which questions the suitability of more detailed classifications, such as described by Cyriax or the Dutch Guidelines for Shoulder Complaints, for the diagnosis of patients with shoulder complaints in general practice.

Adult↗

PubMed2006

Distribution-insensitive cluster analysis in SAS on real-time PCR gene expression data of steadily expressed genes.

Cluster analysis is a tool often employed in the micro-array techniques but used less in the real-time PCR. Herein we present core SAS code that instead of the Euclidian distances takes correlation coefficient as a dissimilarity measure. The dissimilarity measure is made robust using a rank-order correlation coefficient rather than a parametric one. There is no need for an overall probability adjustment like in scoring methods based on repeated pair-wise comparisons. The rank-order correlation matrix gives a good base for the clustering procedure of gene expression data obtained by real-time RT-PCR as it disregards the different expression levels. Associated with each cluster is a linear combination of the variables in the cluster, which is the first principal component. Large set of variables can then be replaced by the set of cluster components with little loss of information. In this way, distinct clusters containing unregulated housekeeping genes along with other steadily expressed genes can be disclosed and utilized for standardization purposes. Simulated data in parallel with the data from a biological experiment were taken to validate the SAS macro. For both cases, good intuitive results were obtained.

Cluster Analysis↗

PubMed2005

[Arthropod community structure and its fuzzy clustering analysis in jujube orchard].

Based on the principles of community ecology and by the method of fuzzy clustering, this paper studied the temporal and quantitative dynamics of the arthropod community and sub-community in jujube orchard (Feidong 2003), aimed to utilize natural enemy resources for pest control. There were 52 species of arthropod belonging to 47 families in the orchard. Arachnida and Cecidomyidae had a higher relative abundance than other families being 0.3465 and 0.2309, respectively. The individuals of the arthropod community were the highest on 8 June and 21 September. The total community and pests-neutral insect sub-community could be clustered into 4 clusters, respectively. For total community, the clusters (T = 0.92) were those on 22 March, 6 April, 22 November, and on other dates, and for pests-neutral insect sub-community, they (T = 0.94) were those on 22 March, 6 April, 8 June, and on other dates. The natural enemy sub-community could be clustered into 3 clusters (T = 0.94), i. e., those on 22 March, on 6 April, and on other dates. The results of cluster analysis partly reflected the seasonal differences of total community and sub-community, while the temporal overlaps of cluster results reflected the complexity of community structure.

Animals↗