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Results for “Multivariate statistics”

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At least 145 records · Page 8Linked to original sources
PubMed1987

An analysis of the nature of depressive phenomena in primary health care utilising multivariate statistical techniques.

The nature of depressive phenomena in primary health care was explored with data obtained from three primary health care clinics situated in the periphery of the city of Calcutta in India. The Self-Reporting Questionnaire (SRQ) and the Screening for Depression Questionnaire (SDQ-9) were used as the first stage and the Clinical Interview Schedule (CIS) and the Hamilton Rating Scale for Depression (Hamilton) as the second stage instruments respectively. Health workers with limited training administered the first stage instruments to consecutive adult clinic attenders. Principal components analysis followed by multiple linear regression analysis and discriminant function analysis were applied to the data. It was concluded that depressive phenomena in primary health care settings were largely undifferentiated in nature.

Adolescent↗
PubMed1981

Prognosis in acquired aplastic anaemia. A multivariate statistical analysis of 80 cases.

Prognostic factors were studied in a series of 80 patients with aplastic anaemia. The most important and easily obtainable individual variables, isolated in a previous univariate statistical analysis, were placed in a linear logistic regression model. A prognostic formula was derived containing the following 4 variables, in decreasing order of significance: (1) reticulocytes, (2) interval from onset of symptoms to first visit, (3) mean red cell volume, and (4) platelets. The prognostic formula permits an estimate of the probability of death within 3 months from the first visit. Its usefulness in several clinical situations, especially those related to bone marrow transplantation, is illustrated.

Adolescent↗
PubMed1982

Seasonal fluctuations in river bacteria as measured by multivariate statistical analysis of continuous cultures.

Forty-eight continuous culture enrichments were performed on summer and winter water samples from two contrasting rivers. The cell output from each chemostat was dependent on the temperature and nitrogen concentration of each enrichment. The diversity of the populations from the continuous cultures, as assessed by species diversity analysis, was always greater than populations obtained on agar plates. However, the species isolated exclusively by continuous culture in these experiments were not unique to the chemostat. All of these species had been isolated at some time on plates directly. High nitrogen concentrations were found to decrease diversity. Populations sampled during the winter were influenced primarily by the concentration of nitrogen. Summer isolates were affected mainly by the temperature of the culture medium. The nutritional versatility of the population was not affected by enrichment of the continuous culture.

Analysis of Variance↗
PubMed1984

EEG-based multivariate statistical analysis of sleep stages.

All-night sleep of 5 healthy male subjects was scored on the basis of EEG (paper records), EMG and EOG into the stages of wakefulness, REM sleep and slow sleep stages 1-4 according to Rechtschaffen and Kales. Spectral analysis for 8 EEG channels was then performed and spectral parameters (total power and coherence for certain frequency bands) extracted. Stepwise linear discriminant analysis was applied to these spectral parameters to see how well the polygraphically defined sleep stages were recognized. While the results of each intrasubject analysis were satisfactory (error rates between 10 and 15%), a more detailed analysis revealed that most errors occur between nearby slow sleep stages or between S1 and REM or wakefulness. This is related to the fact that Rechtschaffen and Kales classify into discrete stages an essentially continuous process and this is, to some extent, arbitrary. This interpretation is supported by examples. Cross-classification of each subject on the basis of the remaining 4 increases the error rates drastically. A simple way of avoiding this effect, by standardizing the individual data, is shown to work nicely in this case.

Adult↗
PubMed1989

[Multivariate statistical analysis in stabilometry in human upright standing (the first report)--age-related factor].

Posturography is not a clearly defined examination. Recently a number of parameters can be obtained in stabilometry by means of computers. To evaluate each parameter and to decide its normal range, subject's age must be considered. The age-related factors found in stabilometry were studied in terms of both multiple regression analysis and cluster analysis. The parameters used in this study were as follows: the area of an ellipse for rejection and of the figure displayed on an X-Y recorder, the maximum width on both the X axis (left and right direction) and the Y axis (anterior and posterior direction), the total length and the sum of excursion in each direction, the root mean square, the velocity, the acceleration, and the averaged frequency of body sway in both X and Y directions. One hundred normal subjects, aged from the second to sixth decade, including 10 males and 10 females in each decade, were tested. Each subject was asked to stand on a platform in Romberg's position for 60 seconds with both eyes open and closed. The significant parameters to predict age, which were determined by multiple regression analysis, were as follows (P less than 0.05): the averaged frequency in the Y direction with eyes closed, the maximum width in the X direction with eyes open, the area of the ellipse for rejection and of the figure with eyes closed, the maximum width in the Y direction and the area of the ellipse and the velocity in the X direction with eyes open. All test subjects were successfully classified into two groups by cluster analysis. One was the younger group aged less than 40 years and the other was the older group not younger than 40-year-old. However, the difference between with eyes open and with eyes closed was not significant (P less than 0.01) as regards the parameters of root mean square and averaged frequency in both sexes and at every decade. The difference between both sexes was supposed to be significant in the Y direction in the younger group and in the X direction in the older one.

Adult↗
PubMed1989

[Multivariate statistical analysis in stabilometry in human upright standing (second report)--pattern recognition of a stabilogram].

A pattern of a figure which is displayed by an X-Y recorder or by a polygraph in stabilometry may present several qualitative facts about the standing ability of a test-subject. The purpose of this study was to make a quantitative evaluation of the body stability in both normal and ataxic patients who were standing erect. The technique utilised was pattern-recognition, composed of principal component analysis and discriminant analysis. Stabilometrical examinations were carried out in 20 normal subjects, 39 with peripheral vestibular disturbance and 11 with disturbance of the central origin. Each examinee was ordered to keep an upright posture for 60 seconds both with the eyes open and with the eyes closed. The following parameters were used: the area of the ellipse for rejection by a statokinesigram, the maximum width and the total length of body excursion, the root mean square, the velocity, the acceleration and the average frequency in the horizontal plane. These were the same parameters that were used in the first report. Each component predicting a specific character in stabilometry was identified by this study of principal component analysis. The relationship between the components in order and its prediction were as follows: the first component predicted the size of the body movement, the second the force, the third the density, the fourth the difference between body movement with the eyes open and with the eyes closed and the fifth the direction of body sway. Furthermore, the principal components were successfully utilized to allow the classification of the test subjects into three groups: those who were normal, those with peripheral vestibular disturbance and those with disturbance of the central origin. Discriminant functions were also used to classify the above mentioned three groups and another five groups, namely: those who were normal, those with vestibular neuronitis, those with positional vertigo of the benign paroxysmal type, those with Ménière's disease and those with cerebellar ataxia. In classification of the three groups, the significant parameters used for discrimination were as follows (P less than 0.05): the root mean square with the eyes open, the distance and the maximum width of body excursion in the Y direction with the eyes open, the area of the ellipse for rejection both with the eyes open and with the eyes closed, the maximum width and the average frequency in the X direction with the eyes closed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Multivariate statistical analysis of electron micrographs of a mammalian transcription initiation complex.

We describe the appearance of the murine ribosomal protein (rp) L32 gene transcription initiation complex as determined by electron image analysis. Using a fractionated nuclear extract enriched for transcription factors necessary for rpL32 gene transcription in vitro and a DNA fragment containing the rpL32 gene promoter, the transcription initiation complex was prepared and viewed by standard transmission electron microscopy. Image analysis demonstrated that the complex was a multilobed structure.

Cells, Cultured↗
PubMed1991

Atherosclerotic lesion of the circle of Willis: its study applying an atherometric system using multivariate statistical techniques.

In 2043 autopsies divided into the high (HAG) and low (LAG) atherosclerosis group a set of variables of a new atherometric system (AS) was used to characterize the atherosclerotic lesion (AL) in the circle of Willis arteries: fatty streaks (X), fibrous plaques (Y), severe plaques (Z), index of stenosis (P) and index of benignity (B). Principal component analysis identified a first component of severity (Y, P and Z) and a second component of benignity (X and B). Fibrous plaques play the main role in the severity of AL in the circle of Willis. The new AS proved its usefulness in characterizing the state of AL, whereas discriminant analysis and AS distinguished between the HAG and the LAG. The classification was correct in 74.5% and 76.5% when using three (X, Y, Z) and five (X, Y, Z, P, B) variables, respectively.

Arteriosclerosis↗