Discriminant Function Equations Research Articles

Identification of sex in Iranian population using patella dimensions

Objectives Heretofore, sex determination has been carried out on skeletal remains to identify individuals in forensic cases and to assess populations in archaeological cases. Since it has been shown that not all bones are found in a forensic case, discriminant function equations should be derived for various bones of the body to assist in sex determination. The aim of this study was to derive discriminant function equations for sex determination from measurements of the patella. Methods In a prospective study, dimensions of patella were measured using the fresh cadavers of Iranian population as referred to the Tehran’s Legal Medicine Organization. Results A total sample of 113 (57 male, 56 female) patellae were measured using three measurements. Stepwise and direct analyses were performed with the average accuracy of 92.9% for sex classification, thereby making the patella useful for sex determination. Conclusions The results of this study confirm the high accuracy of using the measurement of the patella for sex determination. Until further data collected suggests otherwise, the results expected in present study are limited to forensic cases of the Iranian population.

Sex determination using metacarpal biometric data from the Athens Collection

Forensic anthropologists and bioarchaeologists usually determine sex by analyzing quantitative and qualitative characters of the human skeleton. In general, the pelvis and skull are the skeletal parts used most often, but in many cases these parts are missing or fragmentary. In such circumstances, it is necessary to use techniques based on other skeletal elements. The primary aim of this work is to determine whether metacarpals can be used for the determination of sex specifically in a Greek population. A secondary step is to describe and develop linear discriminant function equations for sex determination based on a contemporary Greek population using metacarpal biometric data. The skeletal sample of the modern Greeks is housed at the National and Kapodistrian University of Athens (NKUA) is comprised of 993 metacarpals (left and right), corresponding to 151 adult individuals (84 males and 67 females). The correct sex classification reached an accuracy of 83.7–88.1% for left and 83.8–89.7%, for right metacarpals. Our results suggest that metacarpals can be used for sexing in bioarchaeological, and forensic studies, in addition to other sex determination techniques.

The skull and humerus in the determination of sex: Reliability of discriminant function equations

Sex determination plays a crucial role in the identification of human remains as it narrows the possibility for identification by 50%. The purpose of this study is to test the validity of five discriminant function equations, with accuracies of 80% and higher, that have been derived by Steyn and Işcan [M. Steyn, M.Y. Işcan, Sexual dimorphism in the crania and mandibles of South African Whites, Forensic Sci. Int. 98 (1998) 9–16; M. Steyn, M.Y. Işcan, Osteometric variation in the humerus: sexual dimorphism in South Africans, Forensic Sci. Int. 106 (1999) 77–85] for the skull and humerus of South Africans of European Descent (SAED). These equations were tested on different regional populations of SAED within South Africa. While the validity of some of the discriminant functions has been assessed by the authors who derived them, no other previous independent study has been carried out to assess the reliability of these equations. In addition, these equations have not been tested on skeletons located outside the Gauteng province. The study sample consisted of 230 skulls and 264 humeri of SAED obtained from four South African skeletal collections: Raymond A. Dart Collection of Human Skeletons (Johannesburg); Pretoria Bone Collection; Cape Town Skeletal Collection; and the Osteology Archive Student Collection (Stellenbosch). A total of 14 measurements (12 cranial and 2 humeral) were taken on these skeletal elements. The observed accuracies from the present study (72.0–95.5%), with the exception of one sample's accuracy, compared well with the original classification rates (80.2–92.5%) for most of the functions thereby confirming the validity of the discriminant function equations for sex determination for the skull and humerus of SAED, for SAED in all regions of South Africa.

Determination of Sex for the 12th Thoracic Vertebra by Morphometry of Three‐dimensional Reconstructed Vertebral Models

Thirty-three linear measurements and two ratios were derived from 102 12th thoracic vertebrae of the Digital Korean database at the Catholic Institute for Applied Anatomy. Of 35 linear traits, 23 were sexually dimorphic. We created 23 discriminant function equations that predicted sex with 62.7-85.3% accuracy. The analysis using combinations of two factors gave higher accuracies: most equations with accuracies over 80% included at least one measurement involving the coronal diameter of the vertebral endplate. Using stepwise method of discriminant function analysis, three variables predicted sex with 90.0% accuracy: the coronal diameter of the superior endplate of the vertebral body, the ratio of anterior to middle height of the body, and the length of the left mammillary process and pedicle. Coronal dimensions of the vertebral body represented the major sex difference. These equations will help forensic discrimination of the sex of this vertebra among Koreans.

An assessment of sex using the skull of black South Africans by discriminant function analysis

The derivation of discriminant function equations for skeletal elements of South African populations continues to be an area of interest to both forensic anthropologists and skeletal biologists alike. The skull of black South Africans has previously been subjected to discriminant function analysis, using four measurements and two indices; however, no equations were derived to address the issue of sex determination. Recently Franklin, Freedman and Milne [2005. Sexual dimorphism and discriminant function sexing in indigenous South African crania. HOMO J. Comp. Hum. Biol. 55, 213–228] used the crania of black South Africans, in a three-dimensional approach, with eight linear measurements to investigate sex determination. This study, although valuable, requires the use of highly technical and expensive morphometric equipment that renders it less feasible in South Africa. In response to this, our study uses traditional anthropometric measurements and equipment to address the question of sex determination from the crania and mandible of blacks. One hundred and twenty non-pathological skulls were randomly selected from the Raymond Dart Collection of Human Skeletons, equally distributed by sex and belonging to individuals whose age at death ranges between 25 and 70 years. Fourteen cranial and six mandibular measurements were subjected to discriminant function analyses and discriminant function equations were derived for sex determination. Average accuracies ranged between 80% and 85% and were on par with that obtained in previous studies. Our study shows that traditional methods provide average accuracies that are comparable to those obtained using more complex techniques.

Sex determination from the talus and calcaneus measurements

Several studies have demonstrated that discriminant function equations used to determine the sex of a skeleton are population-specific. The purpose of the present research was to develop discriminant function equations for sex determination on the basis of 18 variables on the right and left talus and calcaneus in a modern northern Italian sample. The sample consisted of 118 skeletons (62 males and 56 females) from the Frassetto Collection (University of Bologna). The ages of the individuals ranged from 19 to 70 years. The results indicated that metric traits of the talus (in particular) and calcaneus are good indicators of sexual dimorphism. The percentage of correct classification was high (87.9–95.7%). In view of the differences among current Italian populations, we tested the validity of the discriminant function equations in an independent sample of individuals of different origin (northern and southern Italy). The accuracy of classification was high only for the northern Italians. Most southern Italian males were misclassified as females, confirming the population-specificity of discriminant function equations.

Discriminating Sex in South African Blacks Using Patella Dimensions

For many years, sex determination has been carried out on skeletal remains to identify individuals in forensic cases and to assess populations in archaeological cases. Since it has been shown that not all bones are found in a forensic case, discriminant function equations should be derived for all bones of the body to assist in sex determination. Numerous studies have shown the usefulness of bones of the lower extremity (e.g. femur, tibia) in sex determination using discriminant function analysis, but the use of patella measurements has not been extensively investigated for this purpose. It is therefore the aim of this study to derive discriminant function equations for sex determination from measurements of the patella of South African blacks as represented in the Raymond A. Dart Collection of Human Skeletons. A total sample of 120 (60 male, 60 female) patellae were measured using six measurements. The Statistical Product and Service Solutions (SPSS) program was used to derive the equations. Stepwise and direct analyses were performed with the highest rate of classification of 85% thereby making the patella useful for sex determination. Thus, the proposed equations derived from this study should be used with caution and only on the South African black population group.

Metrical and non-metrical assessment of population affinity from the calcaneus

To date, there are no metric standards for differentiating between population groups from measurements of the calcaneus in South Africa. Previously, some of the measurements of the calcaneus have been used for sex determination in Americans, Europeans, Italians and South Africans. However, the variations in the number of articular facet present on the superior surface of the calcaneus have been observed in different population groups. This study aims at investigating the potentials of measurements of the calcaneus in diagnosing population affinity and observes population variations of the number of articular facet present on its superior surface in indigenous South Africans and those of European descent. Nine measurements were taken from 180 non-pathological left calcanei in a sample of known sex and population affinity obtained from the Raymond A. Dart Collection of Human Skeletons. Three articular facet types were observed. A significantly higher incidence of type A was observed in South Africans of European descent (SAED) population group while type B predominated in the indigenous South African (ISA) population group. Type C even though rare was found only in ISA group. The metrical data were subjected to discriminant function analyses. The average accuracy in correct classification (81–89%) obtained for the discriminant function equations derived in this study may assist in the determination of population affinity when the calcaneus is present for analysis in forensic cases.

Individuality, willingness to take risk, and use of a personal e‐card

PurposeTo address the issue of risk intention using personal e‐cards and to test the effect of the individuality of decision makers in the Lebanese context.Design/methodology/approachThe data of this research were collected by means of personal interviews using questionnaire. The sample involved 197 managers from various industries. The researchers developed a discriminant function equation to investigate risk taking behavior in the use of e‐cards. The function classifies individuals into risk takers and non‐risk takers on the basis of their psychographics and demographic characteristics. Risk was measured using the risk‐assessment scenario developed by MacCrimmon and Wehrung. Risk intention was measured by asking: “What is the likelihood of your being willing, in the near future, to pay for items on the internet using a personal e‐card?”. Seven items were used to measure psychographics and lifestyle information. Factor analysis was used as a data‐reduction technique, followed by multiple regression analysis (discriminant function) to determine the relative importance of the independent variables.FindingsThe study demonstrated that, although respondents valued risk and were willing to take a chance, they did care about security. Further analysis showed that highly educated managers (university education) and Christians were slightly more willing to pay by e‐card on the internet than were less‐educated and Muslim managers.Research limitations/implicationsIt has to be borne in mind that using dissimilar groups will make the validity of the procedure questionable. Replicating the same study under different conditions (different groups in Lebanon or outside Lebanon) will make prediction more reliable.Practical implicationsThe discriminant analysis in this study has helped to explain the difference between risk taking and non‐risk‐taking managers in Lebanon.Originality/valueThis paper addresses a new issue about risk intention and offers practical explanation. It fulfils an identified need in the Literature. Lebanon is a small country with one of the most developed internet markets in the Arab world but Lebanese People hesitate to transfer money via the internet. The current study was therefore conducted to address the issue of risk intention using personal e‐cards and to test the effect of the individuality of decisionmakers in the Lebanese context.

Further Evidence to Show Population Specificity of Discriminant Function Equations for Sex Determination Using the Talus of South African Blacks

Several studies have shown that osteometric differences exist between different population groups. Thus, discriminant function equations derived for the determination of sex from skeletal elements are population specific. In a previous study, the authors derived such equations from nine measurements of the talus of South African whites with high levels of average accuracies. The validity of some of the equations was tested on data collected from a South African black sample that consisted of 120 tali, equally distributed by sex, derived from the Raymond A. Dart Collection of Human Skeletons. The average accuracies dropped significantly. This necessitated the derivation of new equations for the South African black population and the average accuracies obtained ranged between 80% and 89%. The validity of the equations derived from the present study was tested using the leave-one-out classification and two independent samples (1 and 2). The applicability of the equations with very high classification rate from the present study was tested on Independent sample 1 of 10 white tali with poor results. The result of the validity of these equations on an Independent sample 2 of 10 black tali revealed acceptably high average accuracies in correct classification thereby supporting earlier observations on population specificity of discriminant function equations.

Sexual Dimorphism of the Calcaneus of South African Blacks

Forensic anthropology is a rapidly growing field in South Africa and skeletal biologists are often called upon by the police to assist in personal identification from skeletal remains, which are recovered in suspected cases of homicide and suicide and in mass disaster. Measurements of the calcaneus have been shown to be sexually dimorphic in South African whites. Since the validity of discriminant function equations in sex determination is population specific, the aim of the present study was to derive similar equations for the calcanei of the South African blacks. The bones that were used in this study were obtained from the Raymond A. Dart Collection of Human Skeletons, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg. One hundred and sixteen (116) intact and non-pathological calcanei, consisting of 58 males and 58 females and belonging to individuals whose age at death ranged between 22 and 75 years, were selected by the simple random sampling technique. The measured variables included the maximum length, the load arm length, the dorsal articular facet length, the body height, the maximum height, the cuboidal facet height, the middle breadth, the dorsal articular facet breadth and the maximum breadth. Discriminant function analyses were done using the Statistical Product and Service Solutions (SPSS) program. All measured parameters of the calcaneus showed significant sexual differences. Length measurements were found to be the most sexually dimorphic. Combinations of variables provided better estimate of sex (79%-86%) than individual variables (64%-79%).

Sex determination from the talus of South african whites by discriminant function analysis.

The field of forensic anthropology involves the building of an antemortem profile of an individual from skeletal remains. This includes sex and race determination and age and stature estimation. Since most bones that are conventionally used for sex determination are often recovered either in a fragmented or incomplete state, it has become necessary to use denser bones that are often recovered intact, eg, the patella, calcaneus, and talus. Thus the aim of this study is to assess the sex-determining ability of each of the measurements of the talus and derive discriminant function equations for sex determination in the South African white population. Sixty male and 60 female tali of South African whites obtained from the Raymond A. Dart Collection of Human Skeletons were used. Nine measurements were taken on each talus. Descriptive statistics and discriminant function analysis were performed on the acquired data. The basic statistics showed that all measurements were sexually dimorphic. Univariate, stepwise, and direct discriminant function equations were generated for use in sex determination. The level of average accuracy of sex classification was 80% to 82% for the univariate method, 85% to 88% for the stepwise method, and 81% to 86% for the direct method. It is concluded that the talus of South African whites is useful for sex determination.

Field Identification of the Mice <em>Peromyscus leucopus noveboracensis</em> and <em>P. maniculatus gracilis</em> in Central New York

Field identification of the White-footed Mouse (Peromyscus leucopus noveboracensis) and Long-tailed Deer Mouse (Peromyscus maniculatus gracilis) is difficult because of their similar external morphology. Peromyscus were sampled by live-trapping during a five-year period (1992-1996) at the Arnot Teaching and Research Forest, Van Etten, New York and identified to species by electrophoresis of their salivary amylase. No electromorphs were shared between P. leucopus and P. maniculatus, thus permitting unambiguous species identification of individuals. Means and ranges of four external measurements (ear, head-body, hind-foot, and tail) and tail to head-body ratio were determined for amylase-genotyped live mice. Although some body measurements did differ on average between the two species (ear, head-body, and tail for adults; hind-foot and tail for juveniles), the ranges of these overlap considerably. When the four external measurements (excluding the tail to head-body ratio) were used to construct two discriminant-function equations, they yielded correct identification of 80% of the adult P. l. noveboracensis and P. m. gracilis assessed excluding juveniles, and 71% of adult and juvenile mice combined. The function reported here allows partial field identification, but genetic analysis remains the only reliable field method for differentiation between live P. l. noveboracensis and P. m. gracilis. Includes erratum for a figure in this article.

Identification of Malingered Head Injury on the Wechsler Adult Intelligence Scale – 3rd Edition

Head injured patients show an IQ subtest pattern that can be discriminated from the profile produced by individuals who attempt to malinger intellectual decline due to head trauma. The current paper demonstrates that previously replicated methods for making this discrimination on the WAIS – R generalize to the WAIS – 3. The discriminant function equation accurately classified 83% of nonlitigating head-trauma patients with documented injuries and 72% of persons simulating intellectual impairment due to head trauma. A total of 45% of litigating mild head-trauma patients with purported intellectual decline but no documented loss of consciousness, hospitalization, or CT abnormality were classified as malingering by the discriminant function. A Vocabulary-Digit Span difference score provided 71% overall diagnostic accuracy, and may be informative when screening profiles by visual inspection or when complete WAIS – 3 results are unavailable.

Sex Variation in the Second Cervical Vertebra

The second cervical vertebra can be used to estimate sex with 83% accuracy in unidentified human skeletal remains. Reported here are the necessary statistics, based on 8 dimensions taken from 400 second cervical vertebrae, for the computation of customized discriminant functions. Discriminant function equations developed using variables selected in a stepwise procedure are also presented here as an example of the usefulness of this bone in estimating sex.

Determining the human origin of fragments of burnt bone: a comparative study of histological, immunological and DNA techniques

In situations where badly burnt fragments of bone are found, identification of their human or non-human origin may be impossible by gross morphology alone and other techniques have to be employed. In order to determine whether histological methods were redundant and should be superseded by biomolecular analyses, small fragments of artificially burnt bone (human and non-human) were examined by quantitative and standard light microscopy, and the findings compared with newer biomolecular analyses based on identifying specific human albumin by ELISA and amplifying human mitochondrial DNA by PCR. For quantitative microscopy, reference data were first created using burnt bones from 15 human and 20 common domestic and farm animals. Measured osteon and Haversian canal parameters were analysed using multivariate statistical methods. Highly significant differences were found between values for human and non-human bone, and a canonical discriminant function equation was derived, giving a predicted correct classification of 79%. For the main study, samples of cortical bone were taken from three fresh cadavers, six human skeletons and ten freshly slaughtered animals and burnt by exposure to temperatures ranging from 800 to 1200°C; charred fragments of human cortical bone from two forensic cases were also tested. Quantitative microscopy and canonical discriminant function gave the correct origin of every sample. Standard microscopy falsely assigned burnt bone from one human skeleton and one forensic case to a non-human source, but otherwise gave correct results. Human albumin was identified in five individuals, including one of the forensic cases, but mitochondrial DNA could not be amplified from any of the human bone. No false positive test results were seen with either biomolecular method; and human albumin and mitochondrial DNA were correctly identified in all unburnt control specimens. It was concluded that histological methods were not redundant and that quantitative microscopy provided an accurate and consistent means of determining the human or non-human origin of burnt bone and was more reliable than standard microscopy or the newer immunological and DNA techniques tested here.

Sex estimation using the first cervical vertebra.

The articular surfaces and vertebral foramen area of the first cervical vertebra are sexually dimorphic and can be used to sex complete or fragmentary specimens. Eight measurements were taken from the articular regions (superior and inferior) of 100 first cervical vertebrae from Terry collection specimens housed at the Smithsonian Institution. Seven regression and seven discriminant function equations were created that predict sex with 77-85% and 75-85% accuracy, respectively. In separate control tests, measurements from 100 first cervical vertebrae from Hamann-Todd collection individuals (Cleveland Museum of Natural History) and from 34 archaeological specimens were used with the Terry equations. The control samples were sexed with 60-85% accuracy.

Attentional and behavioral predictors of outcome in adolescent psychiatric inpatients

Cognitive impairment is a predictor of a poor outcome in adult psychotic disorders, but it has received little research attention in adolescent psychialric patients. Recent studies have indicated that impulsivity, including attentional impairments (CPT errors of commission) and observer-rated behaviors, are associated cross-sectionally with conduct disorders and antisocial tendencies in children and adolescents. In this study, 200 adolescent (age range, 13-17) psychiatric inpatients were examined with a battery of cognitive and attentional measures, as well as with psychometric measures of psychiatric symptoms (MMPI) and antisocial tendencies (Psyehopathy Check List; PCL). Six months after discharge, they were contacted and evaluated for the severity of symptomatology and level of functioning. Four different outcomes were identified: Got~t outcome; Rehospitalization; Continued Residential Treatment; or Runaway. Of the first 64 cases followed up, 29 had a good outcome, 23 had been rehospitalized, 6 had continuous treatment, and 6 had run away. None of the cognitive or psychometric measures were able to identify bad outcomes as a group, but the subjects who ran away after discharge had a clear profile of psychometric and attentional characteristics. Runaways made over twice as many dual-task CPT errors of commission (p < 0.001), had significantly higher scores on the PCL (p < 0.001 ), and had significantly more frequent MMPI 4-9 profiles (p <0.01). All three of these indicators independently (p < 0.05) entered a discriminant function equation which significantly (p < 0.001) discriminated the groups and classified the runaways at a level that was 60% greater than chance. Psychiatric diagnosis and substance abuse did not predict outcome. These data suggest that impulsive tendencies are strongly associated with a specific type of negative outcome in adolescent inpatients--running away--and that both psychometric and attentional measures independently assess this dimension. In addition, our preliminary results suggest that the tendency toward rehospitalization is not predicted by cognitive impairment in adolescents.

Development of a Scale for Use in Monitoring Training-Induced Distress in Athletes

In an attempt to identify athletes at risk of training-induced distress, a scale was developed using items from the Profile of Mood States (POMS). POMS data were collected monthly from 170 varsity college swimmers (70 female, 100 male) during four competitive training seasons. The team coaches identified swimmers who showed signs of compromised performance in response to intensive training (i.e., distress), and several series of discriminant function analyses were conducted in attempts to identify these individuals using POMS scale items. Discriminant function equations derived from subsets of items from the entire POMS items pool resulted in a mean prediction rate for identifying distressed swimmers of 93.9% for men and 100% for women. Seven POMS items which entered the equations most frequently served as predictor variables for analyses of a sample of 33 men swimmers. Predictions of distress were conducted at each monthly assessment. The prediction rate of distress achieved with the 7-item set of POMS items averaged 69.1%, and this level of accuracy was 37.0% above the chance rate of prediction (p < 0.05). In a cross-validation on 29 collegiate track and field athletes, the prediction rate of the 7-item scale was 66.7% (p < 0.05). It is concluded that the scale developed in this investigation was effective in identifying swimmers and other endurance athletes who exhibit signs of distress resulting from intensive training.

Examination of pretreatment predictors of attrition in a VLCD and behavior therapy weight-loss program.

Seventeen pretreatment predictors of attrition in a very low-calorie diet (VLCD) and behavior therapy combined weight-loss program (Optifast) were examined. A multiple discriminant function analysis was conducted on historical data in an attempt to distinguish early dropouts (weeks 2-14) from late dropouts (weeks 15-26) from completers. The following seven predictor variables contributed to the significant discriminant function equation: the number of past diets, past emotional difficulties, past physical or emotional difficulties while dieting, expected stress over the next 6 months, the number of close friends, the number of people who annoy the dieter about his or her weight, and the expectation of insurance coverage. In addition, it was found that completers reported a significantly greater number of previous diets than early dropouts.