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PubMed2001

Towards non-invasive screening of skin lesions by near-infrared spectroscopy.

A noninvasive tool for skin tumor diagnosis would be a useful clinical adjunct. The purpose of this study was to determine whether near-infrared spectroscopy can be used to noninvasively characterize skin lesions. In vivo visible- and near-infrared spectra (400--2500 nm) of skin neoplasms (actinic keratoses, basal cell carcinomas, banal common acquired melanocytic nevi, dysplastic melanocytic nevi, actinic lentigines, and seborrheic keratoses) were collected by placing a fiberoptic probe on the skin. Paired t tests, repeated measures analysis of variance and linear discriminant analysis were used to determine whether significant spectral differences existed and whether spectra could be classified according to lesion type. Paired t tests showed significant differences (p < 0.05) between normal skin and skin lesions in several areas of the near-infrared spectrum. In addition, significant differences were found between the lesion groups by analysis of variance. Linear discriminant analysis classified spectra from benign lesions compared with premalignant or malignant lesions with high accuracy. Near-infrared spectroscopy is a promising noninvasive technique for the screening of skin lesions.

Analysis of Variance↗
PubMed2000

Diagnostic assessment of cutaneous melanoma and common nevi using tissue counter analysis.

OBJECTIVE: To test the applicability of tissue counter analysis to the diagnostic discrimination of cutaneous malignant melanoma and benign common melanocytic nevi. STUDY DESIGN: Forty cases each of melanoma and nevi were consecutively sampled. After creation of a learning set based on 20 cases each, discriminant analysis of background versus tissue elements, tumor versus other tissue elements and benign versus malignant tumor elements was performed. The discriminant functions were used to assess the amount of benign and malignant tumor elements in each case. RESULTS: In the learning set, discriminant analysis facilitated recognition of 99.6% of tissue versus background, 90.7% of tumor versus other tissue components and 85.6% of malignant versus benign tumor elements. In the whole set, the percentage of malignant tumor elements was 8.7 +/- 7.7 (range, 0.1-29.6) for benign nevi and 77.4 +/- 16.2 (43.6-99.4) for malignant melanoma. Based on these measurements, the correct diagnosis could be established in all cases (chi 2 > .0001). CONCLUSION: Tissue counter analysis may be a useful method for diagnostic purposes in histopathology.

Adult↗
PubMed1993

Validity of the Dissociative Experiences Scale in screening for multiple personality disorder: a multicenter study.

OBJECTIVE: The Dissociative Experiences Scale has proved a reliable and valid instrument to measure dissociation in many groups, but its capacity to distinguish patients with multiple personality disorder from patients with other psychiatric disorders has not yet been conclusively tested. METHOD: A discriminant analysis was performed to classify 1,051 subjects as having or not having multiple personality disorder. Another discriminant analysis was performed on a subgroup of 883 subjects more closely representing patients in a typical psychiatric facility in terms of base rates of dissociative disorders. A cutoff score of 30 was also used to classify subjects, and Bayes's theorem, which allows for the calculation of the positive predictive value and the negative predictive value of a screening test, was applied. RESULTS: According to discriminant analysis of the total study group, the scale's sensitivity was 76% and its specificity was also 76%; according to discriminant analysis of the more representative subgroup, the scale's sensitivity was 76% and its specificity was 85%. Use of the cutoff score of 30 produced similar results. Results of the application of Bayes's theorem showed that 17% of the subjects scoring 30 or higher would actually have multiple personality disorder and 99% of those scoring less than 30 would not have multiple personality disorder. CONCLUSIONS: These results indicate that the Dissociative Experiences Scale performs quite well as a screening instrument to identify subjects with multiple personality disorder. In addition, the consistency of responses to scale items across centers indicates that the symptoms reported by patients with multiple personality disorder are highly similar across diverse geographic centers. This consistency supports the reliability and validity of the diagnosis of multiple personality disorder across centers.

Adult↗
PubMed2002

A statistical technique for the development of an alternate list when using constrained optimization to make admission decisions.

BACKGROUND: In an earlier study it was demonstrated that constrained optimization could be used to accurately translate admission goals. Constrained optimization differs from weighting equations in that it does not assign a rank ordering. Although constrained optimization is conceptually superior, some procedures within the admissions process require a rank ordering of applicants. PURPOSE: The purpose of this study is to describes and evaluate the use of two discriminant analysis procedures to obtain a rank order list by generating weights that model constrained optimization procedures. This study also evaluates the usefulness of an additional method that does not require a rank ordering. METHODS: Premium Solver selected a class from the 1998/99 applicant pool. A discriminant analysis was used to generate a discriminant function for modeling the dichotomous group classification selection variable. These weights were then applied and the discriminant function values calculated. The success of the procedure was evaluated by examining rank orders and the magnitude of the correlation and R-square statistic. RESULTS: Discriminant analysis accounted for 70% of the decision variance generated by the constrained optimization procedure. Using real data allowed an estimate of the number of students impacted by inconsistent outcomes. CONCLUSION: Discriminant analysis could be used to manage an alternate list, however it will be based on somewhat different criteria than the initial selection procedure. Each method evaluated has advantages and disadvantages and the selection of one method over another depends on what outcomes are most valued by the college.

Discriminant Analysis↗
PubMed1996

Morphometric variation in Plio-Pleistocene hominid distal humeri.

The magnitude and meaning of morphological variation among Plio-Pleistocene hominid distal humeri have been recurrent points of disagreement among paleoanthropologists. Some researchers have found noteworthy differences among fossil humeri that they believe merit taxonomic separation, while others question the possibility of accurately sorting these fossils into different species and/or functional groups. Size and shape differences among fossil distal humeri are evaluated here to determine whether the magnitude and patterns of these differences can be observed within large-bodied, living hominoids. Specimens analyzed in this study have been assigned to various taxa (Australopithecus afarensis, A. africanus, A. anamensis, Paranthropus, and early Homo) and include AL 288-1m, AL 288-1s, AL 137-48a, AL 322-1, Gomboré IB 7594, TM 1517, KNM-ER 739, KNM-ER 1504, KMN-KP 271 (Kanapoi), and Stw 431. Five extant hominoid populations are sampled to provide a standard by which to consider differences found between the fossils, including two modern human groups (Native American and African American), one group of Pan troglodytes, and two subspecies of Gorilla gorilla (G.g. beringei, G.g. gorilla). All possible pairwise d values (average Euclidena distances) are calculated within each of the reference populations using an exact randomization procedure. This is done using both raw linear measurements as well as scale-free shape data created as ratios of each measurement to the geometric mean. Differences between each pair of fossil humeri are evaluated by comparing their d values to the distribution of d values found within each of the reference populations. Principal coordinate analysis and an unweighted pair group method with arithmetic averages (UPGMA) cluster analysis are utilized to further assess similarities and differences among the fossils. Finally, canonical variates analysis and discriminant analysis are employed using all hominoid samples in order to control for correlations among variables and to identify those variables that discriminate among groups; possible affinities of individual fossils with specific extant species are also examined. The largest size differences, those between the small Hadar specimens and the two largest fossils (KNM-ER 739, IB 7594), can be accommodated easily within the ranges of variation of the two Gorilla samples, but are extreme relative to the other reference samples. The d values between most of the fossils based on shape data, with the notable exception of those associated with KNM-ER 739 and KNM-ER 1504, can be sampled safely within all five reference samples. Subsequent analyses further support the inference that KNM-ER 739 and KNM-ER 1504 are different from the other hominid humeri and possess a unique total morphometric pattern. In overall shape, the distal humeri of the other fossils (non-Koobi Fora) are most similar to living chimpanzees. The distal humerus of Paranthropus from Kromdraai (TM 1517e) is most similar to one of the Hadar specimens of A. afarensis (AL 137-48a), whereas the first specimen of A. africanus from Sterkfontein (Stw 431) is not closely linked to any of the other australopithecines. The A. anamensis humerus from Kanapoi exhibits no special affinities to A. afarensis or to modern humans.

Animals↗
PubMed1997

Quantitative chromatin pattern description in Feulgen-stained nuclei as a diagnostic tool to characterize the oligodendroglial and astroglial components in mixed oligo-astrocytomas.

The oligoastrocytoma, as a mixed glioma, represents a nosologic dilemma with respect to precisely defining the oligodendroglial and astroglial phenotypes that constitute the neoplastic cell lineages of these tumors. In this study, cell image analysis with Feulgen-stained nuclei was used to distinguish between oligodendroglial and astrocytic phenotypes in oligodendrogliomas and astrocytomas and then applied to mixed oligoastrocytomas. Quantitative features with respect to chromatin pattern (30 variables) and DNA ploidy (8 variables) were evaluated on Feulgen-stained nuclei in a series of 71 gliomas using computer-assisted microscopy. These included 32 oligodendrogliomas (OLG group: 24 grade II and 8 grade III tumors according to the WHO classification), 32 astrocytomas (AST group: 13 grade II and 19 grade III tumors), and 7 oligoastrocytomas (OLGAST group). Initially, image analysis with multivariate statistical analyses (Discriminant Analysis) could identify each glial tumor group. Highly significant statistical differences were obtained distinguishing the morphonuclear features of oligodendrogliomas from those of astrocytomas, regardless of their histological grade. When compared with the 7 mixed oligoastrocytomas under study, 5 exhibited DNA ploidy and chromatin pattern characteristics similar to grade II oligodendrogliomas, I to grade III oligodendrogliomas, and I to grade II astrocytomas. Using multifactorial statistical analyses (Discriminant Analysis combined with Principal Component Analysis). It was possible to quantify the proportion of "typical" glial cell phenotypes that compose grade II and III oligodendrogliomas and grade II and III astrocytomas in each mixed glioma. Cytometric image analysis may be an important adjunct to routine histopathology for the reproducible identification of neoplasms containing a mixture of oligodendroglial and astrocytic phenotypes.

Adult↗
PubMed1978

Linear discriminant function analysis in neuropsychological research: some uses and abuses.

The present paper addressed the continued misinterpretation and misapplication of linear discriminant function analysis in neuropsychological research. Methodological problems concerning the influence of shrinkage and stepwise selection procedures on LDFA are virtually ignored and affect both the classification and inferential application of LDFA. Throughout the paper examples of potential abuses of LDFA were cited and data from a familiar research problem was employed to demonstrate procedures which enable more accurate interpretation of LDFA results. Linear discriminant function analysis and its multivariate equivalents are powerful and flexible tools for exploring group differences provided appropriate applications and interpretations of results are made.

Craniocerebral Trauma↗
PubMed2002

Response of liver and heart trace elements in rats to the interaction between dietary zinc and iron.

An analysis of the interaction between dietary iron (Fe) and zinc (Zn) was performed by using data from Sprague-Dawley rats in a 5 x 4 fully crossed factorially arranged experiment. The concentrations of 9 trace elements from the liver and 10 from the heart were determined and subjected to diverse statistical analyses and were classified by their response to the interaction between dietary Fe and Zn. The interaction was studied by using analysis of variance (ANOVA), discriminant analysis, and logistic regression to determine the direction of interaction; that is, did dietary Fe affect dietary Zn or did dietary Zn affect dietary Fe? The use of discriminant analysis allowed for using multiple parameters (rather than a single parameter) to determine possible interactions between Fe and Zn. Thus, two main levels of interaction were studied: the separate response of each tissue mineral and the response of some grouped minerals. The responses studied were the effect of dietary Zn on tissue trace element parameters, the effect of dietary Fe on the parameters, the effect of dietary Zn on combined (grouped) parameters, and the effect of dietary Fe on combined parameters. As determined by ANOVA, only three individual trace elements--liver Fe, Cu, and Mo--were significantly affected by the interaction between Fe and Zn. However, a broader interaction between Fe and Zn is revealed when groups of, rather than single, trace elements arestudied. For example, an interaction between dietary Fe and Zn affects the weighted linear combination of heart Ca, Cu, K, Mg, Mn, P, and Zn. This article presents the hypothesis that grouped parameters may be useful as status indicators. The complete dataset can be found at http://www.gfhnrc.ars. usda.gov/fezn.

Analysis of Variance↗
PubMed1988

Discriminant function analysis of clinical laboratory data. Use in alcohol research.

There has been a growing interest in the use of discriminant function analysis of routinely collected laboratory data to differentiate between alcoholic and nonalcoholic individuals. However, no consensus has been reached concerning the validity and reliability of this form of analysis regarding the diagnosis of, or screening for, alcoholism. In addition, this technique may provide important information concerning the multivariate nature of the pathophysiological effects of alcohol. However, this issue is seldom discussed. Because of differences in methodology across studies and the growing confusion regarding conceptual issues associated with this statistical technique, there have been few critical reviews. This chapter is directed at critically evaluating the current literature, particularly with respect to the methodological and conceptual issues associated with the use of discriminant function analysis in alcohol research. As part of this approach we suggest guidelines for future research in this area.

Alcoholism↗
PubMed1993

Physician satisfaction with rural hospitals.

This study examines factors leading to physician satisfaction with small rural hospitals. Interviews were conducted with 122 rural physicians using a standardized survey instrument. The relationship between the independent variables and the dependent variable, hospital satisfaction, are described and tested using chi-square and discriminant analysis. The findings of this study revealed that no demographic variables appeared in the chi-square, and only age appeared in the discriminant analysis. Practice factors impacting hospital satisfaction included practice satisfaction (both in the chi-square and discriminant analysis) and years at current location (only in the chi-square). Hospital-related factors affecting hospital satisfaction included administrative responsiveness (strongest association); administration accessibility, communication with administration, and nursing skill and knowledge in the chi-square; and administrative responsiveness, nursing skill and knowledge, and technology in the discriminant analysis.

Adult↗
PubMed2004

Karyometry detects subvisual differences in chromatin organisation state between non-recurrent and recurrent papillary urothelial neoplasms of low malignant potential.

AIM: To analyse nuclear chromatin texture in non-recurrent and recurrent papillary urothelial neoplasms of low malignant potential (PUNLMPs). MATERIALS: Ninety three karyometric features were analysed on haematoxylin and eosin stained sections from 20 PUNLMP cases: 10 from patients with a solitary PUNLMP lesion, who were disease free during at least eight years' follow up, and 10 from patients with unifocal PUNLMP, one or more recurrences being seen during follow up. RESULTS: Kruskal-Wallis analysis was used to search for features showing significant differences between recurrent and non-recurrent cases. Significance was better than p<0.005 for more than 20 features. Based on significance, six texture features were selected for discriminant analysis. Stepwise linear discriminant analysis reduced Wilk's lambda to 0.87, indicating a highly significant difference between the two multivariate data sets, but only modest ability to discriminate (70% correct case classification). A box sequential classifier was used based on data derived from discriminant analysis. The classifier took three classification steps and classified 19 of the 20 cases correctly (95% correct case classification). To determine whether significant case grouping could also be obtained based on an objective criterion, the merged data sets of non-recurrent and recurrent cases were submitted to the unsupervised learning algorithm P-index. Two clusters were formed with significant differences. The subsequent application of a Cooley/Lohnes classifier resulted in an overall correct case classification rate of 85%. CONCLUSIONS: Karyometry and multivariate analyses detect subvisual differences in chromatin organisation state between non-recurrent and recurrent PUNLMPs, thus allowing identification of lesions that do or do not recur.

Algorithms↗
PubMedDate not supplied

[Variations in lymphocyte subsets in chronic inflammatory and neoplastic pathology in the elderly. II. Discriminant stepwise analysis].

The variations of lymphocyte subsets in chronic inflammatory and neoplastic diseases in an elderly population, have been previously reported. The different behavior of all the subsets that had shown significant variations of frequencies and absolute values within the groups with the Multivariate Analysis of Variance, have been studied. The use of the Discriminant Stepwise Analysis has given the chance to spot the discriminant subsets and their ability in discriminating the inflammatory and the neoplastic groups from each other and from the controls and finally in pointing out all the subsets which did not affect such differentiation.

Aged↗
PubMed2000

Acoustic identification of twelve species of echolocating bat by discriminant function analysis and artificial neural networks.

We recorded echolocation calls from 14 sympatric species of bat in Britain. Once digitised, one temporal and four spectral features were measured from each call. The frequency-time course of each call was approximated by fitting eight mathematical functions, and the goodness of fit, represented by the mean-squared error, was calculated. Measurements were taken using an automated process that extracted a single call from background noise and measured all variables without intervention. Two species of Rhinolophus were easily identified from call duration and spectral measurements. For the remaining 12 species, discriminant function analysis and multilayer back-propagation perceptrons were used to classify calls to species level. Analyses were carried out with and without the inclusion of curve-fitting data to evaluate its usefulness in distinguishing among species. Discriminant function analysis achieved an overall correct classification rate of 79% with curve-fitting data included, while an artificial neural network achieved 87%. The removal of curve-fitting data improved the performance of the discriminant function analysis by 2 %, while the performance of a perceptron decreased by 2 %. However, an increase in correct identification rates when curve-fitting information was included was not found for all species. The use of a hierarchical classification system, whereby calls were first classified to genus level and then to species level, had little effect on correct classification rates by discriminant function analysis but did improve rates achieved by perceptrons. This is the first published study to use artificial neural networks to classify the echolocation calls of bats to species level. Our findings are discussed in terms of recent advances in recording and analysis technologies, and are related to factors causing convergence and divergence of echolocation call design in bats.

Acoustics↗
PubMed2002

Predicting revascularization outcome in patients with coronary artery disease and left ventricular dysfunction (data from the SEMINATOR study).

A main goal of revascularization in patients with chronic ischemic cardiomyopathy is to improve global left ventricular (LV) function. This study aimed to verify whether it is possible to predict an increase in LV ejection fraction (EF) after revascularization on the basis of the extent of LV asynergy, myocardial viability, and revascularization completeness. We studied 77 patients with chronic LV ischemic dysfunction using baseline resting and nitrate-enhanced technetium-99m sestamibi single-photon emission computed tomography. Regional wall motion and global LVEF were assessed with echocardiography before and after revascularization, which was complete in 51 patients and incomplete in 26. The number of viable asynergic segments included in revascularized coronary artery territories was the strongest predictor of significant (> or = 5 EF U) functional improvement in univariate discriminant analysis. According to multivariate stepwise discriminant analysis, this parameter, together with the number of baseline asynergic segments, allowed the detection of patients with significant LVEF improvement with 75% accuracy. With use of a multivariate regression model, including the 2 mentioned variables, the measure of postrevascularization LVEF increase could be accurately quantified (R(2) 0.43, p <0.000001). In conclusion, this study suggests that the severity of baseline asynergy, the extent of myocardial viability, and the completeness of revascularization are the main determinants of postrevascularization functional recovery in patients with LV ischemic dysfunction, and that on the basis of these variables it is possible to predict the measure of LVEF increase.

Coronary Disease↗
PubMedDate not supplied

Brain tumor classification by proton MR spectroscopy: comparison of diagnostic accuracy at short and long TE.

BACKGROUND AND PURPOSE: Different TE can be used for obtaining MR spectra of brain tumors. The purpose of this study was to determine the influence of the TE used in brain tumor classification by comparing the performance of spectra obtained at two different TE (30 ms and 136 ms). METHODS: One hundred fifty-one studies of patients with brain tumors (37 meningiomas, 12 low grade astrocytomas, 16 anaplastic astrocytomas, 54 glioblastomas, and 32 metastases) were retrospectively selected from a series of 378 consecutive examinations of brain masses. Single voxel proton MR spectroscopy at TE 30 ms and 136 ms was performed with point-resolved spectroscopy in all cases. Fitted areas of nine resonances of interest were normalized to water. Tumors were classified into four groups (meningioma, low grade astrocytoma, anaplastic astrocytoma, and glioblastoma-metastases) by means of linear discriminant analysis. The performance of linear discriminant analysis at each TE was assessed by using the leave-one-out method. RESULTS: Tumor classification was slightly better at short TE (123 [81%] of 151 cases correctly classified) than at long TE (118 [78%] of 151 cases correctly classified). Meningioma was the only group that showed higher sensitivity and specificity at long TE. Improved results were obtained when both TE were considered simultaneously: the suggested diagnosis was correct in 105 (94%) of 112 cases when both TE agreed, whereas the correct diagnosis was suggested by at least one TE in 136 (90%) of 151 cases. CONCLUSION: Short TE provides slightly better tumor classification, and results improve when both TE are considered simultaneously. Meningioma was the only tumor group in which long TE performed better than short TE.

Adolescent↗
PubMed1991

Interoperator variability in quantitative electroencephalography.

The purpose of the study was to determine whether quantitative or discriminant analysis of the electroencephalograph (EEG) would vary significantly when the same EEG was analysed by 3 different operators. EEGs on 10 healthy volunteers were recorded on the Cadwell Spectrum AT 386, using the Electrocap (10-20 system). The EEGs were analysed independently, with each operator selecting the first 48 artifact-free epochs. The results were analysed using the non-parametric Friedman two-way analysis of variance (ANOVA) for the discrimination analysis and a one-way ANOVA for the monopolar and bipolar Absolute Power raw measures. Statistical analysis of the discriminant data showed no significant differences between operators, with 7 of 10 studies yielding the same results. The remaining 3 studies were classified either as borderline or normal when analysed by different operators. Although a series of "t" tests comparing 2 operators showed most variability occurring in Absolute Power as compared with Relative Power, Power Asymmetry and Coherence, ANOVA of the raw mono- and bipolar Absolute Power measures showed no significant differences between the operators at the P = 0.05 level. Thus the differences between the operators were non-significant when comparing quantitative EEG analyses with respect to both the raw measures and the discriminant analyses.

Analysis of Variance↗
PubMed1998

Handedness identification from intertubercular sulcus of the humerus by discriminant function analysis.

The accurate determination of skeletal handedness is a critical requirement in physical anthropology and forensic science. To differentiate handedness, discriminant function analysis is applied using the parameters of right and left intertubercular sulci. A total of 200 matched unpaired adult humeri (100 right and 100 left), collected from the Department of Anatomy, were used to measure four parameters of the intertubercular sulcus namely, width (X1), depth (X2), angle of medial wall (X3) and angle of lateral wall (X4) and to note the presence of supratubercular ridge of Meyer (X5). The discriminant function obtained with the significant variables, angle of medial wall (X3), angle of lateral wall (X4) and presence of the supratubercular Meyer (X5) is: Y = 0.093X3 + 0.056X4 + 0.775X5 - 13.46. The accuracy of correct classification using the discriminant function is 89% which is the best starting point for handedness determination approach. The methodology of using discriminant function can be crucial for medicolegal jurisprudence.

Adult↗
PubMed1997

Assessment of the appropriateness of the decision of heart transplantation in idiopathic-dilated cardiomyopathy.

One hundred thirty patients with idiopathic-dilated cardiomyopathy were referred for heart transplantation to our center and followed for 18 months. Heart transplantation was performed on 63 patients, 17 patients died before transplantation due to heart failure, and 50 patients never had transplantation. Clinical, electrocardiographic, echocardiographic, and hemodynamic data of the 50 nontransplanted survivors and the 17 patients who died were used to identify independent risk variables with discriminant analysis. Using a statistical model based on the results of discriminant analysis, each of the remaining 63 transplanted patients were predicted as being alive or dead in absence of transplantation. The discriminant analysis identified right atrial pressure, cardiac index, and the New York Heart Association functional class as the strongest predictors of 18-month outcome. The accuracy of the model in predicting survival without transplantation in the nontransplanted group of patients, based on the concordance between actual and predicted outcome, was 85% (kappa = 0.62). Subsequent application of this model to the transplanted group of patients suggested that the decision for transplantation was appropriate in 41 of the 63 patients, and could have been premature in the remaining 22 patients predicted as alive. These results suggest that two-thirds of patients receiving transplants would have died without intervention, but the decision to transplant could have been premature in the remaining patients.

Adult↗