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PubMed1985

Incremental value of the exercise treadmill test in determining the extent of coronary artery disease: a discriminant function analysis.

This study was undertaken to determine whether it was possible to use a multivariate discriminant function analysis to assess the severity of coronary artery disease in patients with angina pectoris. One hundred and forty-three patients diagnosed as having angina pectoris who formed a 'learning group' were subjected to an exercise test on a treadmill using a Bruce protocol. The items of data from the test least likely to be influenced by beta blockade were considered for the analysis along with two discrete variables (the gender and the use of beta blockers). All the patients subsequently underwent coronary angiography and the severity of the coronary artery disease was graded according to a scoring system. In addition, patients in 'learning group' were classified into two 'Groups', (I) those with normal vessels or with disease in one or two of the major arteries, (II) those with disease in the left main stem or in all three major arteries. The multivariate analysis yielded a score based upon 4 factors: (i) gender, (ii) percentage increase in double product at the highest level of exercise achieved, (iii) duration of ST depression in the recovery period and (iv) the summation of the ST depression in the standard electrocardiogram excluding lead aVR. There was a significant overall correlation between the discriminant function score and the coronary artery score for severity of the disease. In addition, it was found that, of patients having discriminant function score below 0, 96% (69/72) were in Group I. The post-test risk of a positive test was 0.005.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1998

Four addictions: the MMPI and discriminant function analysis.

Over the past twenty years many MMPI studies of substance abuse have investigated the complex relationship between personality profile and drug of choice. This work has repeatedly established that alcoholics, heroin, cocaine and polydrug addicts share 4-2/2-4 (Psychopathy and Depression) or 4-8/8-4 (Psychopathy and Thought Disorder) MMPI profiles, but that the substance abuse populations differ in the plane of severity in that general profile. The alcoholics occupy the least disturbed sector, the polydrug abusers the most disturbed level and the heroin and cocaine addicts positions of moderate disturbance. The vast majority of studies, however, cite only group means to buttress their conclusions. Our work probed more deeply into the data using Discriminant Function Analysis. With this methodology we discovered important differences between the groups, previously hidden, which may carry differential treatment implications.

Adult↗
PubMed2003

[Study on the application of artificial neural network on diabetes mellitus/insulin-glucose tolerance classification].

OBJECTIVE: To discuss the potential application of artificial neural network (ANN) on the epidemiological classification of disease. METHODS: Learning vector quantification neural network (LVQNN) and discriminate analysis were applied to data from epidemiological survey in a mine in 1996. RESULTS: The structure of LVQNN was 25-->13-->3. The total veracity rates was 96.98%, and 92.45% among the abnormal blood glucose individuals. Through stepwise discriminate analysis, the discriminate equations were established including 11 variables with a total veracity rate of 87.34%, but was 85.53% in the abnormal blood glucose individuals. Further analysis on 30 cases with missing values showed that the disagreement ratio of LVQ was 1/30, lower than that of discriminate analysis of 7/30. CONCLUSIONS: Compared to the conventional statistics method, LVQ not only showed better prediction precision, but could treat data with missing values satisfactorily plus it had no limit to the type or distribution of relevant data, thus provided a new powerful method to epidemiologic prediction.

Algorithms↗
PubMed2006

Authentication of the botanical origin of honey by near-infrared spectroscopy.

Fourier transform near-infrared spectroscopy (FT-NIR) was evaluated for the authentication of eight unifloral and polyfloral honey types (n = 364 samples) previously classified using traditional methods such as chemical, pollen, and sensory analysis. Chemometric evaluation of the spectra was carried out by applying principal component analysis and linear discriminant analysis. The corresponding error rates were calculated according to Bayes' theorem. NIR spectroscopy enabled a reliable discrimination of acacia, chestnut, and fir honeydew honey from the other unifloral and polyfloral honey types studied. The error rates ranged from <0.1 to 6.3% depending on the honey type. NIR proved also to be useful for the classification of blossom and honeydew honeys. The results demonstrate that near-infrared spectrometry is a valuable, rapid, and nondestructive tool for the authentication of the above-mentioned honeys, but not for all varieties studied.

Discriminant Analysis↗
PubMed2004

Computerized evaluation of mammographic lesions: what diagnostic role does the shape of the individual microcalcifications play compared with the geometry of the cluster?

OBJECTIVE: The objective of this study was to compare the diagnostic role of features reflecting the geometry of clusters with features reflecting the shape of the individual microcalcification in a mammographic computer-aided diagnosis system. MATERIALS AND METHODS: Three hundred twenty-four cases of clustered microcalcifications with biopsy-proven results were digitized at 42-microm resolution and analyzed on a computerized system. The shape factor and number of neighbors were computed for each microcalcification, and the eccentricity of the cluster was computed as well. The shape factor is related to the individual microcalcification; the average number of neighbors and the cluster eccentricity reflect the cluster geometry. Stepwise discriminant analysis was used to evaluate the contribution of the extracted features in predicting malignancy. The performance of a classifier based on the features selected by stepwise discriminant analysis was evaluated by receiver operating characteristic (ROC) analysis. RESULTS: To obtain the best discrimination model, we used stepwise discriminant analysis to select the average number of neighbors and the shape of the individual microcalcification, but excluded cluster eccentricity. A classification scheme assigned the average number of neighbors a weighting factor, which was 1.49 times greater than that assigned to the shape factor of the individual microcalcification. A scheme based only on these two features yielded an ROC curve with an area under the curve (A(z)) of 0.87, indicating a positive predictive value of 61% for 98% sensitivity. CONCLUSION: Computerized analysis permitted calculations reflecting the shape of individual microcalcification and the geometry of clusters of microcalcifications. For the computerized classification scheme studied, the cluster geometry was more effective in differentiating benign from malignant clusters than was the shape of individual microcalcification.

Adult↗
PubMed1996

Sex determination by discriminant function analysis of the petrous portion of the temporal bone.

Morphometric variables on the human petrous portion of the temporal bone can provide identification of sex in fragmented skeletal remains. The petrous frequently survives circumstances that cause skeletal fragmentation. Using discriminant function analysis of seven combinations of five variables, up to 74% accuracy can be obtained in determining sex from the petrous portion.

Discriminant Analysis↗
PubMed1994

Developing an effective adult nutrition screening tool for a community hospital.

OBJECTIVE: To develop a sensitive and specific nutrition screening tool that conforms to the requirements of the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) and is effective in any given hospital population. DESIGN: A two-step prospective evaluation was performed in two unrelated community hospitals to determine the effectiveness of a current nutrition screening tool, and to develop a new, more sensitive tool that permits efficient use of available personnel. STATISTICAL ANALYSES: Standard calculations for sensitivity, specificity, positive predictive value, and negative predictive value were used to compare the results of various screening methods with those of full nutrition assessments. Stepwise discriminant analysis was used to determine specific parameters that contributed to the diagnosis of malnutrition and to derive a predictive equation based on these parameters. METHODS: In part 1, 100 patients admitted consecutively were evaluated using a subjective screening tool; the results were compared with those from full nutrition assessment of the same patients. Stepwise discriminant analysis identified three parameters most closely related to malnutrition, and a multivariant equation relative to nutrition risk was derived. In part 2, 151 randomly selected adult medical and surgical patients were evaluated at admission with the same screening tool used in part 1. Additionally, prealbumin level was determined on admission. The results of the screening, the discriminant analysis equation from part 1, and both methods incorporating the prealbumin level were compared with the results of a full nutrition assessment. RESULTS: In part 1, discriminant analysis identified total lymphocyte count, percentage weight loss, and serum albumin level as the three best indicators of malnutrition. A multivariant equation incorporating these objective parameters was derived. In part 2, the equation yielded better sensitivity and specificity results than other screening methods. Inclusion of prealbumin level did not improve screening methods. CONCLUSIONS: The revised screening tool described can be used as the basis of an effective screening program that meets the proposed JCAHO nutrition care standards.

Adult↗
PubMed1997

Sexual determination of the femur using discriminant functions. Analysis of a Spanish population of known sex and age.

Until present, functions for sexual discrimination of a Spanish population from series of known sex and age were not available. In this work, we present a sample of 132 femora (72 females and 60 males) belonging to a Spanish population of adult individuals of known filiation deposited in the Complutense University of Madrid. The ten mathematical functions which yield a higher sexual discrimination in each part of the femur, were selected. The resulting percentages of correspondence varied between 84 and 97% when each variable was considered independently, and a 99% is obtained with two variables of the epiphyses combined.

Adult↗
PubMed2004

Scaling affordances for human reach actions.

A methodology developed by Cesari and Newell [Cesari, P., & Newell, K. M. (1999). The scaling of human grip configuration. Journal of Experimental Psychology: Human Perception and Performance 25, 927-935; Cesari, P., & Newell, K. M. (2000). The body-scaling of grip configurations in children aged 6-12 years. Developmental Psychobiology 36, 301-310] was used to delineate the roles of an object's weight (W) and distance (D) as well as the actor's strength (S) in determining the macroscopic action used to reach for the object. Participants reached for objects of five different weights placed at 10 distances. The findings of a single discriminant analysis revealed that when object weight is scaled in terms of each individual's strength and reach distance is scaled in terms of each individual's maximum-seated reach distance, a single discriminant analysis was able to predict 90% of the reach modes used by both men and women. The result of the discriminant analysis was used to construct a body-scaled equation, K=lnD+ln(W/S)/36, similar in form to the one derived by Cesari and Newell, accurately predicted the reach action used. Our findings indicate that Cesari and Newell's method can identify a complex relationship between geometric and dynamic constraints that determine the affordances for different reach actions.

Adult↗
PubMed2008

The Assessment of Depression Inventory (ADI): an appraisal of validity in an outpatient sample.

In this study we examined the validity of the Assessment of Depression Inventory (ADI) using outpatient participants. The ADI Depression scale (Dep) was compared to three other measures used to assess depression: Beck Depression Inventory-II (BDI-II), Zung Self-Rating Depression Scale (ZSDS), and Personality Assessment Inventory (PAI). Correlations between the ADI and these three measures were significant. An analysis of the discriminant ability of the ADI Dep scale resulted in sensitivities, specificities, positive predictive power, negative predictive power, hit rate, and area under the curve (92.3%) that were supportive of the scale's effectiveness. The ADI Feigning scale (Fg) was compared to the six PAI validity scales. The Fg scale correlated significantly with the PAI Negative Impression Management (NIM) and Positive Impression Management (PIM) scales, and the Malingering (MAL) and Defensive (DEF) indexes. Directionality was as would be predicted. The ADI did not correlate with the two PAI validity scales derived by discriminant analysis function.

Ambulatory Care↗
PubMed2006

Application of multivariate statistical methods to water quality assessment of the watercourses in Northwestern New Territories, Hong Kong.

Multivariate statistical methods, i.e., cluster analysis (CA) and discriminant analysis (DA), were used to assess temporal and spatial variations in the water quality of the watercourses in the Northwestern New Territories, Hong Kong, over a period of five years (2000-2004) using 23 parameters at 23 different sites (31,740 observations). Hierarchical CA grouped the 12 months into two periods (the first and second periods) and classified the 23 monitoring sites into three groups (group A, group B, and group C) based on similarities of water quality characteristics. DA provided better results with great discriminatory ability for both temporal and spatial analysis. DA also provided an important data reduction because it only used six parameters (pH, temperature, five-day biochemical oxygen demand, fecal coliforms, Fe, and Ni) for temporal analysis, affording about 84% correct assignations, and seven parameters (pH, ammonia-nitrogen, nitrate nitrogen, fecal coliforms, Fe, Ni, and Zn) for spatial analysis, affording more than 90% correct assignations. Therefore, DA allowed a reduction in the dimensionality of the large data set and indicated a few significant parameters that were responsible for most of the variations in water quality. Thus, this study demonstrated that the multivariate statistical methods are useful for interpreting complex data sets in the analysis of temporal and spatial variations in water quality and the optimization of regional water quality monitoring network.

Discriminant Analysis↗
PubMed1998

Identifiers of predominantly Spanish-speaking children with language impairment.

The purpose of this study was to identify a set of measures that would discriminate 31 predominantly Spanish-speaking children with normal language (NL children) from 31 children with language impairment (LI children). The LI children were identified as such by experienced, bilingual (Spanish/English), ASHA-certified, speech-language pathologists who were currently seeing the children in their caseloads. Children ranged in age from 5 to 7 years and were matched for age, gender, and school. Additionally, nonverbal cognitive measures assured that they did not differ significantly intellectually. Measures of vocabulary, novel bound-morpheme learning skills, and language form were randomly administered to all children. Further, parents responded to questions about their perceptions of their children's speech and language skills and family history of speech and language problems. A stepwise discriminant analysis indicated that 4 measures discriminated the groups of children with a sensitivity of 91.3% and a specificity of 100% (p < .0001): parental report of the child's speech and language skills, number of errors per T-unit, mean length per T-unit, and family history of speech and language problems. A second discriminant analysis indicated that the sensitivity and specificity could be maintained when only the first 2 measures were included. Confirmatory discriminant analyses of the 2- and 4-measure models indicated that the discriminant accuracy was stable on an independent sample.

Child↗
PubMed1998

The value of PCNA and AgNOR staining in endoscopic biopsies of gastric mucosa.

The aim of the present study was to examine the usefulness of the quantification of PC10-positive-cells and of Argyrophilic Nucleolar Organizer Regions (AgNORs) in gastric biopsies for the identification of gastric mucosal proliferative lesions. Fifty seven paraffin-embedded endoscopic biopsies were classified into four histologic groups: normal, inflammatory, dysplastic and neoplastic mucosa. The percentage of PC10-positive cells was determined by immunohistochemistry. The AgNOR parameters determined included the total number of all identifiable silver precipitations in the nucleus, the mean number of silver precipitations per cluster, and the presence of morphologically heterogenous silver precipitations. Group comparisons were performed using the Kruskall Wallis and Dunn non-parametric tests with a significance level of 5%. A discriminant analysis (followed by the jack-knife procedure) was performed using the three AgNOR parameters plus the percentage of PCNA-positive cells as the independent variables and histological groups as the dependent variable. All three AgNOR parameters, as well as the percentage of PCNA-stained nuclei, showed their highest values in the carcinoma group. However, no good differentiation among the four histologic groups was obtained using only one of these parameters, since there was always considerable overlap among them. By combining all the parameters in a linear discriminant analysis, we obtained a correct classification in 48 out of 57 cases. Within the classification errors there was only one false positive carcinoma, which was in fact a dysplasia and only one false negative carcinoma erroneously classified as dysplasia. The number of cells with heterogenous AgNORs was the most important parameter for the discriminant analysis. No correlation between PCNA values and the AgNOR parameters could be found, thus indicating that they do not represent the same phenomenon in the cell cycle. We concluded that the use of a combination of various proliferation parameters in a linear discriminant analysis may be helpful for differentiating gastric mucosal lesions. The peculiar AgNOR morphology is an important variable which should be taken in consideration in quantitative studies. PCNA and AgNORs seem to represent different physiological phenomena in the cell cycle.

Adenocarcinoma↗
PubMed1994

Skeletal jaw relationships: a quantitative assessment using elliptical Fourier functions.

Elliptical Fourier functions (EFF) were generated for the boundary outlines of the hard tissue craniofacial complex including the maxilla, mandible, and cranial base in order to quantitatively describe adult patients (n = 98) who were initially classified into nine skeletal groups by a combination of conventional cephalometric measures and clinical judgement. The mean residual fit of the EFF-predicted points and the original digitized data for the individual subjects ranged from .42 mm to .61 mm with a mean of .52 mm suggesting an accurate fit. Visual inspection of the individual plots confirmed this. Predicted classifications from a step-wise discriminant analysis based on EFF amplitudes were compared with the original classifications. The discordance rates for A-P and vertical plane classification were 21% and 13% respectively with an overall discordance rate of 33%. In general, a cluster analysis using EFF amplitudes did not identify clusters very similar in membership to the original groups; however, it was marginally successful in identifying members of the more severe groups and, like discriminant analysis, appeared to be more sensitive to vertical morphological differences. The overall lack of agreement between classifications and clusters based on EFF amplitudes and the original classifications may indicate that traditional skeletal categories such as those used in this study do not actually represent discrete groups.

Adolescent↗
PubMed2006

Are American College of Rheumatology 50% response criteria superior to 20% criteria in distinguishing active aggressive treatment in rheumatoid arthritis clinical trials reported since 1997? A meta-analysis of discriminant capacities.

OBJECTIVE: To carry out a meta-analysis designed to compare the discriminant capacities of American College of Rheumatology 50% (ACR50) with 20% (ACR20) responses in clinical trials on rheumatoid arthritis reported after 1997 and to analyse whether ACR50 can be as informative as ACR20 in distinguishing active from control treatments in more recent trials. METHODS: Clinical trials on rheumatoid arthritis reported since 1997 were identified, which included aggressive combinations of disease-modifying antirheumatic drugs and glucocorticoids, as well as powerful new agents-leflunomide, etanercept, infliximab, anakinra, adalimumab, abatacept, tacrolimus and rituximab. A meta-analysis of ACR20 compared with ACR50 responses for 21 clinical trials was carried out on differences in proportions of responders for active and control treatments and corresponding odds ratios (ORs). RESULTS: In all but one clinical trial on rheumatoid arthritis published since 1997 with data available on ACR20 and ACR50, more than 50% of patients who were ACR20 responders among those randomised to active treatment were also ACR50 responders. This phenomenon was seen for control groups in 38% of trials, many of which included treatment with methotrexate. A meta-analysis of the clinical trials indicated a slight advantage to ACR50 for quantifying treatment comparisons, not significant for differences in proportions but significant for ORs. CONCLUSION: ACR20 and ACR50 seem to be similar in distinguishing active from control treatments in clinical trials on rheumatoid arthritis reported since 1997. As ACR50 represents a considerably stronger clinical response, ACR50 may be a preferred end point for contemporary clinical trials on rheumatoid arthritis.

Antirheumatic Agents↗
PubMedDate not supplied

Structural equation modeling for conducting tests of differences in multiple means.

Multivariate methods for analyzing group differences in means on dependent variables include multivariate analysis of variance, discriminant analysis, and multivariate analysis of factor means. To make appropriate choices among these methods, researchers should understand the statistical models underlying them. We present these models using path diagrams within a structural equation modeling framework. Results for the different methods are presented for an example concerning coping with asthma.

Adaptation, Psychological↗
PubMed1983

Multiple discriminant function analysis of sex and race in the postcranial skeleton.

Terry Collection femora and innominates of 260 American Whites and Blacks (65 males and 65 females of each race) were analyzed by multiple discriminant function analysis. A stepwise procedure produced three optimal discriminant functions using 15 of our 32 measurements. These functions correctly identified 95% of the sample. The first two-one for sex and one for race-are statistically and biologically significant and form the basis of our analysis. The sexing function manifested both size and shape elements. Prominent among the former was joint size--acetabular diameter and epicondylar diameter of the femur. The shape elements included form of the greater sciatic notch and of the inferomedial aspect of the pubic body. The racing function highlighted a pattern of greater innominate dimensions, exclusive of the acetabular joint, in Whites. This was in contrast to the greater length of the Black femur. Overall, the function seems to express the established differences between the races in the ratio of lower limb length to torso length. While these functions have been applied successfully to forensic cases with confirmed identifications, questions regarding the breadth of applicability of discriminant functions make it desirable to validate our results on new material from the Terry and other collections.

Analysis of Variance↗