Separate Discriminant Functions Research Articles

Estimation of sex based on metrics of the sternum in a contemporary Jordanian population: A computed tomographic study.

There is a paucity of osteometric standards for sex estimation from unknown skeletal remains in Jordan and the sexual dimorphism of the sternum has not yet been investigated. The aim of this study was to evaluate the sexual dimorphism in sternal measurements using 3D multidetector computed tomography (MDCT), and to assess their reliability for sex estimation in a Jordanian population. A total of 600 MDCT scans (300 males and 300 females) were used and a total of 8 sternal measurements were studied (manubrium length, sternal body length, combined length of manubrium and body, corpus sterni width at 1st and 3rd sternebrae, sternal index and area). Sexual dimorphism was evaluated by means of discriminant function analyses. Significant sexual dimorphism was found mainly in middle-aged and older adults. Including all subjects, multivariate, and stepwise functions gave an overall accuracy of 83.0% and 84.0%, respectively. Additionally, multivariate and stepwise analyses were conducted separately for each age group. The accuracy of sex estimation in multivariate analysis (all variables) varied from 63.2% in the young, and 83.7% in the middle adults to 84.9% for older adults. In stepwise analysis, the highest accuracy rates were provided by only sternal area in young adults (81.6%), and sternal area combined with sternal body length in middle-aged and older adults (84.2% and 85.3%, respectively). The best sex discriminator using univariate analysis (single variable) was sternal area followed by sternal body length (84.0% and 80.8% respectively). Notably, univariate analyses for most variables gave relatively higher classification accuracies in females but were poor at predicting males in the sample (sex bias ranged between −6.4% and −20%). Our data suggest that dimorphism in the human sternum increases with advancing age and separate discriminant functions are needed for each age group in Jordanians. In addition, multivariate and stepwise analyses using sternum gave higher classification accuracies with comparatively lower sex biases compared to univariate analyses.

A pilot study on assessment of racial affinity of Sri Lankan population using discriminant function statistics and a few established morphological racial traits

Determination of racial affinity was not considered in investigations of unidentified bones in Sri Lanka until recently. Post-Tsunami exhumation of mass graves to identify Japanese and Europeans tourists highlighted the lack of anthropological data to separate them from Sri Lankans. Objective The objective of this study is to determine the racial affinity of the Sri Lankan population using few well documented anatomical traits and Giles and Elliot’s discriminant function analysis. Methodology Following measurements were obtained from 38 skulls. Basion–Prosthion length, Maximum length, Maximum breadth, Basion–Bregma height, Basion–Nasion height, Bizygomatic breadth, Prosthion–Nasion height and Nasal breadth. Results Giles and Elliot (1963)’s discriminant functions developed to determine ancestry were used. In addition, few well-established morphological racial traits were also observed. Separate discriminant functions developed by Giles and Elliot to differentiate American white skulls from black skulls and white skulls from native Indian skulls were used. Five skulls had the measurements of blacks and another five had the measurements of Native Americans. The rest had measurements of American whites. 24 skulls had ‘medium’ (intermediate triangle) nasal openings. Nasal root contour was low to moderate in height (tented) in 22 skulls. Nasal spine was small in 31 skulls and nasal sill was blurred in 27 skulls. Conclusion Discriminant functions developed by Giles and Elliot identified the majority of skulls in this study as belong to Caucasians but only few skulls had obvious Caucasian morphological traits. However, there were few skulls showing clear Negroid and Mongoloid morphological features. Finally this study showed that the formulae developed by Giles and Elliot can be used to differentiate Sri Lankan skulls from those of American Indians and Blacks.

Using Morphometrics To Determine the Sex of Common Ravens

Abstract We tried using morphometrics to determine sex for a population of Common Ravens (Corvus corax) in northwestern Wyoming. We attempted to correlate 13 external measurements to sex using discriminant function analyses. Sex was verified with a DNA test that identified females with 2 PCR-amplified gene copies (1 each from the W and Z chromosomes) and males with 1 gene copy (only Z chromosome). We created a predictive model of sex of ravens for easy field use. We found that by using 2 separate discriminant functions with footpad length and body mass measurements simultaneously, we were able to correctly classify 97% of female samples, 91% of male samples, and had an unknown category that included 15% of samples.

Provisioning calls of the cooperatively breeding bell miner Manorina melanophrys encode sufficient information for individual discrimination

Acoustically‐mediated individual discrimination has been the focus of much investigation in ornithology. For cooperatively breeding species, strong selection pressure favouring individual recognition during acts of altruism is predicted under many of the most interesting hypotheses proposed to account for helping behaviour. We investigated differences in 157 calls given by 12 different individuals as they provisioned nestlings, including both breeding and helper bell miners Manorina melanophrys (Meliphagidae), a cooperatively breeding honeyeater endemic to south‐eastern Australia. Individual differences were apparent in all 15 call parameters analysed, many with a high level of repeatability. Moreover, the information capacity of mew calls allows as many as 515 different signatures to exist in the system. As many parameters showed strong sex differences, separate discriminant functions were used to predict individual identity within each sex. Five parameters were used in a function that correctly identified over 90% of female calls in both a training (n=35) and test dataset (n=11) not used to generate the function. Among males, a separate function used six parameters to correctly assign individual identity in 89.3% (n=84; training) and 77.8% (n=27; test) of cases. Three original parameters, including spectral and spatial characteristics, were highly correlated with functions predicting identity in both sexes. The accuracy of functions was not influenced by a signaller's sex, breeding status, or by sampling period which was spread over as much as two breeding seasons within individuals. Significant potential therefore exists for bell miners to use these simple provisioning calls in individual discrimination. If this is the case, call information also has the potential to be used by receivers as predicted by signalling hypotheses proposed to account for cooperative helping behaviour, such as the pay‐to‐stay and social prestige hypotheses.

Using carapace measurements to determine the sex of Antarctic krill, Euphausia superba

Krill (Euphausia superba) carapace measurements (length and width; mm) collected from plankton tows in the South Shetland Islands (SSI), Antarctica are used to test the generality of a common discriminant function developed to reconstruct krill length frequencies in Antarctic fur seal diets for the area surrounding South Georgia (SG). Total length and sex ratio of krill in the SSI were overestimated by 5.6 and 154%, respectively, when the SG allometric equations were applied to 3 years (2003–2005) of data. These errors arise and increase as a result of krill population dynamics, specifically recruitment that contributes large proportions of immature krill, misclassified as males by the SG discriminant function. We develop sex-specific regression models based on separate discriminant functions that provide significantly better discriminatory power. However, our analysis indicates that reconstructions of krill sex ratio and length composition in the ocean environment are less reliable in years when the ratio of immature to mature krill is high. For the SSI area, five out of 14 years (35.7%) surveyed (1992–2005) had proportions of immature to mature adult krill ≥ 0.50.

Classification of juvenile flatfishes to estuarine and coastal habitats based on the elemental composition of otoliths

The elemental composition of otoliths from juvenile English sole Pleuronectes vetulus and speckled sanddab Citharichthys stigmaeus living in estuaries and sandy coastal habitats were compared to determine if a chemical habitat tag existed that could be used to differentiate fish living in the alternative juvenile habitats. Juveniles of both species were collected from seven estuaries and 11 coastal sites along 500 km of the central California coast. Collections occurred in three years: 1998, 1999 and 2000. The chemical composition of the otoliths was analyzed using solution-based inductively coupled plasma mass spectrometry. The multi-elemental composition (Sr, Li, Ba, Mn) of otoliths from estuarine and coastal fish differed significantly for all models (global, region and years models) examined in this study. For each species, discriminant function analysis (DFA) for the global model, which pooled juveniles collected from three regions over multiple years, classified fish into estuarine and coastal groups with close to 80% accuracy. The two main elements in the discriminant models, Sr and Li, differed consistently between habitats; Sr was higher and Li was lower in estuarine fish. Classification success was modestly improved by generating separate discriminant functions for each region (regions model) because of some regional differences in Sr and Li concentrations. Classification success also was improved in some cases by generating separate discriminant functions for each year (years model) because Ba and Mn differed between habitats in only some years. Despite this variability in the concentration of elements in some regions and years, a chemical habitat tag was present in each species that could be used to discriminate coastal and estuarine juveniles over a large geographic area and over three years with very different oceanographic conditions (e.g., El Niño, La Niña). In addition, I found that English sole and speckled sanddab had striking similarities in their chemical habitat tags and that, in some cases, one species could be used as a proxy to classify juveniles of the other species without compromising the accuracy of the habitat tag. The ability to use a proxy classification model would significantly reduce the number of juvenile fish that would need to be collected and analyzed in order to classify members of an ecologically similar species. The chemical habitat tags found in this study appears to be promising tools for identifying fish that have lived in alternative juvenile habitats and, ultimately, the proportional contribution of estuarine and coastal habitats to the central California populations of English sole and speckled sanddab.

Identification of twenty‐two bat species (Mammalia: Chiroptera) from Italy by analysis of time‐expanded recordings of echolocation calls

AbstractSpectral and temporal features of echolocation calls emitted by 22 bat species from Italy (three rhinolophids, 18 vespertilionids and the molossid Tadarida teniotis) are described. Time‐expanded recordings of calls from 950 bats of known identity were examined. Rhinolophus ferrumequinum, R. hipposideros, R. euryale and T. teniotis could be identified by measuring the call frequency of highest energy (FMAXE). Quadratic discriminant function analysis with cross‐validation was applied to calls from the remaining 18 species. A function based on start frequency (SF), end frequency (EF), FMAXE and duration (D) provided a correct overall classification of approximately 82%. A classification model at genus level that also comprised middle frequency (MF) and inter‐pulse interval (IPI) reached 94% correct classification. Two separate discriminant functions were devised for species emitting FM (frequency modulated) and FM/QCF calls (i.e. calls consisting of a frequency‐modulated component followed by a terminal part whose frequency is almost constant) respectively. The former function included SF, EF, FMAXE and D and provided an overall classification rate of 71%; the latter comprised EF, MF, D and IPI, and reached 96%. The functions may be applied to bat habitat surveys in southern Italy since they cover most of the species occurring in the area.

Morphometric study of the Pissodes strobi complex (Coleoptera: Curculionidae)

AbstractMorphometric data were collected on 15 characters in adults of the species of the Pissodes strobi complex (P. nemorensis (Germar), P. schwarzi Hopkins, P. strobi (Peck), and P. terminalis Hopping). Data were examined using stepwise discriminant analysis to determine if all characters contribute significantly to the diagnosis of taxa, and their relative amounts of resolving power were illuminated using canonical variates analysis. Discriminant functions were generated to diagnose species. Separate discriminant functions were generated for each sex for populations from eastern and western North America. Significant sexual dimorphism and variability in body size decrease the utility of morphological characters for diagnosis, but did not prevent the formulation of useful discriminant functions, particularly when selected ratios that control for body size were added.

Luria memory words test and Wechsler memory scale: Comparison of utility in discriminating neurologically impaired from controls

Memory deficits are among the most common initial complaints of patients who are suffering from neurological disorders. The present study compared the relative clinical utility of the Wechsler Memory Scale and the Luria Memory Words Test in differentiating brain-damaged (N = 60) from non-brain-damaged patients (N = 60). Separate stepwise regression analyses selected five variables from each test that accounted for the greatest between-group variance. Separate discriminant functions then were computed that used the WMS and the Luria Words variables selected through the regression analyses. The WMS correctly classified 72% of the subjects, whereas the Luria Words correctly classified 76% of the subjects. A final discriminant function was computed that used all 10 variables and resulted in a classification accuracy of 86%, with 6% false positives and 6% false negatives. Results are discussed relative to the use of each instrument in both a general psychological assessment situation and when specific memory functioning is in question.

Use of the MMPI in predicting psychotherapeutic persistence in groups of male and female outpatients.

Attempted to predict therapeutic persistence, as measured by the total number of sessions attended, with the MMPI. High persisters were defined as patients who attended six or more sessions, while low persisters were patients who attended fewer than six sessions. Ss were 360 (180 high persisting, 180 low persisting) female outpatients and 204 (102 high persisting, 102 low persisting) male outpatients. All groups were divided into equal halves in order to allow for cross-validation of three separate discriminant functions: One for males, one for females, and one for the entire sample (male + female). Cross-validation revealed that only the discriminant function for males achieved a classification accuracy (60%) greater than chance expectations. A series of biserial correlations indicated that male persisters tended to be less defensive while experiencing greater distress and that female persisters tended to be more introverted and less impulsive relative to their respective low-persisting counterparts.

Personality and Student Teaching Success

The relationship between personality factors of education students and their success in student teaching was explored in relation to the student teacher’s sex and level of pupils taught. The IPAT Sixteen Personality Factor Questionnaire was administered to all education majors at Florida Atlantic University and the student teaching grade was collected for those students (N = 362) completing the education program.A 3 × 2 × 2 Manova was employed wherein the level of pupil taught, teacher sex, and student teaching grade served as independent variables and the 16 personality scores as dependent variables. Significant effects were grade achieved in student teaching and sex. Separate discriminant functions were derived to separate both males and females with respect to student teaching grade. The percentage of hits resulting from subsequent classification of a replication sample was found too low to validate the personality discriminant model as a student teaching grade predictor.