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Results for “Factor Analysis, Statistical”

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At least 19 recordsLinked to original sources
PubMed1977

Statistical analysis of factors affecting survival after glioblastoma multiforme.

Statistical evaluation of 71 cases (adults) of histologically confirmed supratentorial surgically treated glioblastoma multiforme seen during the period 1958 to 1973 revealed that the state of calcification as determined by roentgenography and the histological appearance of the neoplasm appeared to have a relationship with the postoperative period of survival. Postoperative adjuvant treatment, location of the neoplasm, duration of preoperative symptoms, patient's age at onset, preoperative condition, and cystic formation in the neoplasm also appeared to have a relationship, although it was slight.

Adult↗
PubMed1979

Multivariate analysis and quantitative structure-activity relationships. Inhibition of dihydrofolate reductase and thymidylate synthetase by quinazolines.

Quantitative structure-activity relationships (QSAR) have been established for the inhibition of dihydrofolate reductase and thymidylate synthetase by 2,4-diaminoquinazoline-glutamic acid analogues. For dihydrofolate reductase from both human acute lymphocytic leukemia cells and murine L1210R cells, QSAR's obtained with 50 quinazolines were similar. On the other hand, for the inhibition of thymidylate synthetase from murine L1210S cells and from Lactobacillus casei, QSAR's formulated on the basis of data measured with 33 compounds were different, indicating that the two enzymes are dissimilar. The use of multivariate statistics including cluster analysis, factor analysis, and discriminant analysis is shown to facilitate the formulation of a satisfactory correlation equation. The procedure is demonstrated by the development of QSAR for the inhibition of thymidylate synthetase.

Analysis of Variance↗
PubMedDate not supplied

[Statistical study of the relationships between the etiology and clinical picture of cerebral palsy].

846 children with cerebral palsy were examined and 642 were selected for a statistical study by correspondence analysis. The aim was to identify without any prior assumptions, the relationships between the aetiological factors and the clinical findings. The study was completed by conventional statistical analysis of 584 of the cases. Small birth weight and a history of abnormal pregnancies was associated with a cerebral palsy affecting both legs, and often with a squint. Resuscitation was associated with athetosis and abnormalities of posture and behaviour. If the resuscitation lasted for more than 15 minutes or there were certain problems during delivery, severe abnormalities of both arms and major speech difficulties were observed. Resuscitation for less than 15 minutes or for an unknown time or intractable vomiting during pregnancy was associated with quadraplegia. Hemiplegia was related to post natal events but the aetiology was not always known. Foeto-maternal incompatibility was associated with athetosis, deafness, severe speech problems and ophthalmoplegias.

Abortion, Threatened↗
PubMed1975

[Application of correspondance factor analysis to function testing of the thyroid].

Biological data concerning 249 thyroid patients have been treated by using correspondance factor analysis. This statistical treatment has enabled us to compare 2 types of associated tests (in vitro, in vivo) and to evaluate their respective contribution to the diagnosis of different thyroid diseases. There appeared also certain possibilities for the use of such a method in the future: determination of a biological profile for thyroid disease and for Grave's disease patients in course of treatment.

Binding, Competitive↗
PubMed1976

Statistical analysis of the different factors which could affect postextrasystolic potentiation in the human heart.

The effect of different coupling indices and intervals that could theoretically affect postextrasystolic potentiation has been investigated. A total of 150 ventricular premature beats corresponding to 20 patients submitted to routine cardiac catheterization were studied. Only single ventricular premature contractions following at least four regular sinus beats were considered. Percentage changes in left ventricular systolic pressure, end-diastolic pressure, and max dp/dt were correlated against seven indices and intervals. Index 2 (coupling interval/coupling interval + postextrasystolic pause) gave the better correlations. Besides, this Index includes two intervals that were demonstrated to have statistical significance when individually considered. It has been proved that in the first postextrasystolic beat the highest values of max dt/dt, or left ventricular systolic pressure occurred in early ventricular premature beats, giving a negative regression with Index 2, while in the second postextrasystolic beat the highest values of max dp/dt and left ventricular systolic pressure corresponded to late prematuring beats, giving therefore positive regressions with Index 2 (slope inversion phenomenon). The third and fourth postextrasystolic beats had similar positive regressions but with progressively smaller slopes. Correlations between left ventricular end-diastolic pressure and Index 2 were very poor. It is suggested that variations in baroreceptor activity could account for the different forms of potentiation observed in early and late extrasystoles. In five cases, there were no consistent differences in potentiation when premature beats were elicited from either right or left ventricles.

Adult↗
PubMed1979

Multivariate analysis of cancer mortalities for selected sites in 24 countries.

In order to analyze the pattern in the geographical distribution of cancer death in 24 countries of the world, correlation coefficients were calculated between pairs of mortality rates of different cancer sites, using the data for 13 sites in males and 14 sites in females over 18 years from 1950 to 1967. Then factor analysis by means of varimax method was performed on 13 x 13 correlation matrix for males, 14 x 14 correlation matrix for females and 27 x 27 correlation matrix for males and females combined. As a result of factor analysis, three factors are extracted, which are commonly recognized in both males and females. The first factor has high positive factor loadings on pancreas, prostate (for males), skin, and intestine cancers, and negative loadings on stomach and liver cancers. The second factor has high positive factor loading on rectum, intestine, and lung cancers, and the third factor on larynx, oral, and esophagus cancers. Factor analysis based on 27 x 27 correlation matrix revealed that the third factor of both sexes are heterogeneous with regards to the distributions of the factor score. In order that we may find some clues to develop an etiological hypothesis for each site of cancer, we obtained the correlation coefficient between the scores of the extracted factors and the variables on food and environmental agent, and performed stepwise regression methods as well. One of the most striking results we obtained was that excessive drinking of alcohol and the lack of appropriate intake of fruit are suspected as etiological promoters in the pathogenesis of oral, esophagus, and larynx cancers in males.

Adult↗
PubMed1976

A factor analysis of body build in the rat.

Following a survey of the problems associated with the comparative study of measures of physique in domesticated and laboratory animals, techniques were developed for the measurement of body build in the adult albino laboratory rat (Rattus norvegicus). They involved anesthetisation of the animals and the use of calipers and a simple apparatus devised for the purpose. The 17 measures taken on 100 rats, 50 of each sex, are detailed and the reasons for excluding other given. Intercorrelations of all the measures and their reliability co-efficients, which were judged satisfactory, are presented. The tables of intercorrelations, one for each sex, were factor analysed separately, and rotations to simple structure performed. Two factors were identified, one having factor saturations on measures of body length and the other similarily defining body width. This pattern was similar for the two sexes and a single index of body build was therefore proposed in which the length of the rear foot is divided by the width of the shoulder girdle and multiplied by 100 to avoid decimals. The use of the index in other investigations is mentioned.

Animals↗
PubMed1976

The dimensionality of the human visual evoked scalp potential.

A small number of processes can account for most of the evoked potentials activity in the two subjects studied. Principal components analysis indicates that six independent processes can account for approximately 97% of the variability in the data. Moreover, the factor analysis and plots of the factor coefficients yield indications that the times during which these principal factors are active agree quite well with the times at which the equipotential maps show some organized activity. The question of dipoles being the underlying cause of the observed activity is not answered by the factor analysis. The principal factors are not unique, but models which have a small number of parameters are more justifiable in light of the results of this study.

Brain↗