Point Biserial Coefficient Research Articles

Assessing the oral English proficiency of the Faculty of Fountain international School: Inputs to in-service training

Accepted: 05.10.2013 This descriptive-correlation study attempted to assess and correlate the level of oral English proficiency and selected profile variables of 79 faculty of the Fountain International School (Philippines), consisting of 8 pre-elementary school, 29 elementary school and 42 high school teachers. A researcher-made questionnaire consisting of 25 items which were content validated covers five (5) dimensions, namely; pronunciation, vocabulary, grammar, fluency and intonation. The assessment was made by the unit head, peers and the teachers themselves, including selected students in the case of elementary and high school teachers. The obtained raw data were treated statistically using the percentage, weighted mean, ration coefficient, and point biserial coefficient of correlation. Likewise, the ANOVA was used to test the significant difference in the assessment of the groups of respondents. From the findings revealed in the study, the researcher is moved to conlcude that pre-elementary, elementary and high school teachers of the school respondent are “much proficient” in their oral English, with varying level of proficiency. Also apparent from the findings has lead to construing that the high school teachers are more proficient than the elementary and pre elementary teachers. Their level of proficiency varies in relation to their profile. Among others, fluency and vocabulary need to be emphasized in teachers’ in service training.

Radiology ExamWeb: Development and Implementation of a National Web-Based Examination System for Medical Students in Radiology

Faculty are often limited in time, knowledge, and resources to develop efficient, effective, and valid computer-based examinations to evaluate students. Our purpose was to develop a web-based pool of standardized National Board of Medical Examiners (NBME)-format, peer-reviewed, and peer-tested questions based on the Alliance of Medical Student Educators in Radiology (AMSER) National Medical Student Curriculum to evaluate the radiologic knowledge of medical students. Members of the AMSER Electronics Committee submitted questions they had written for their institutions and later developed a 113-question standardized examination. Questions were edited by 24 subspeciality editors and then further edited by the authors to NBME recommendations. Software was developed using commercially available software (www.ExamWeb.com) with extensive modifications and additions following initial deployment. Students take examinations online and receive their scores immediately. Items were validated by identifying those answered >30 times and analyzing the following: number of times deployed, number of times correctly answered, distractor-specific breakdown, difficulty level (P), and point biserial coefficient (rbi). Radiology ExamWeb (REW) is available online with 3500 registered students from 65 institutions and 1800 active questions. Instructors can create examinations or use "shared examinations" made by another instructor but enabled for other institutions to administer or modify. More than 300 shared examinations have been developed. The AMSER curriculum was converted into database format and crosschecked with question items to ensure that the question pool adequately covered the spectrum of the curriculum. An AMSER standardized examination has been developed and deployed within REW. REW has provided medical student educators with the means to evaluate students in a systematic way, using a nationally edited and regularly reviewed web-based process.

Assessing the Conceptual Understanding about Heat and Thermodynamics at Undergraduate Level

In this study, a Thermodynamic Concept Test (TCT) was designed to assess student’s conceptual understanding heat and thermodynamics at undergraduate level. The different statistical tests such as item difficulty index, item discrimination index, point biserial coefficient were used for assessing TCT. For each item of the test these indices were calculated. For the entire test, test reliability and Ferguson’s delta was calculated. Analysis of data shows that the students have serious difficulties in understanding of heat and thermodynamics in particular and physics in general when taught through traditional teaching method.

Students' Beliefs toward Mathematics as Related to Their Performance in College Algebra

The study was to determine the beliefs of SLSU-San Juan BSED freshmen towards mathematics and their performance in college algebra. Data gathered were analyzed and interpreted using Weighted Mean, Percentages, Pearson r, and the Point Biserial coefficient of correlation. Findings showed that students' educational background is 62% and 38% from public and private respectively. Majority (66%) strongly agreed that mathematics is a challenging subject and 34% considered the latter as one of the difficult subjects. Relationship between beliefs about mathematics and performance in college algebra is statistically significant at 0.05. Relationship between students' educational background and performance in college algebra was found to be not significant. The study proved that male students have better performance in college algebra than female. Students with positive beliefs about mathematics performed better in the subject. Educational background of the students was not a determinant for having good performance in college algebra. Considering the result of the study, teaching development program focusing on giving the importance of belief in teaching college algebra was recommended. Thus, values formation towards mathematics will be integrated in lesson planning to build positive beliefs.

Development of the Concise Data Processing Assessment

The Concise Data Processing Assessment (CDPA) was developed to probe student abilities related to the nature of measurement and uncertainty and to handling data. The diagnostic is a ten question, multiple-choice test that can be used as both a pre-test and post-test. A key component of the development process was interviews with students, which were used to both uncover common modes of student thinking and validate item wording. To evaluate the reliability and discriminatory power of this diagnostic, we performed statistical tests focusing on both item analysis (item difficulty index, item discrimination index, and point-biserial coefficient) and on the entire test (test reliability and Ferguson’s delta). Scores on the CDPA range from chance (for novices) to about 80% (for experts), indicating that it possesses good dynamic range. Overall, the results indicate that the CDPA is a reliable assessment tool for measuring targeted abilities in undergraduate physics students.

Relationships between Psychological Empowerment with Work Motivation and Withdrawal Intention among Secondary School Principals in Malaysia

This study attempts to investigate factors that influence the psychological empowerment with work motivation and work withdrawal intention of school principals in Malaysia. The sample population comprised school principals. A total of 101 selfadministered questionnaires were analysed. Pearson product moment correlation coefficients (Pearson r's) or Point bi-serial (rpb) coefficients were computed between the psychological empowerment total scores and those of the independent variables (or subvariables). Total scores from the four psychological empowerment dimensions and the PE-Overall were correlated individually with scores from the independent variables of Work Motivation and Work Withdrawal Intention. Results indicated all five aspects of psychological empowerment (PE-Overall, PE-Meaning, PE-Competence, PE-Self-determination and PE-Impact) correlated positively and significantly with the Intrinsic Work motivation domain. This study also proves that when withdrawal intentions increased, the dimensional component levels of psychological empowerment decreased correspondingly.

Development and Use of a Conceptual Survey in Introductory Quantum Physics

Conceptual surveys have become increasingly popular at many levels to probe various aspects of science education research such as measuring student understanding of basic concepts and assessing the effectiveness of pedagogical material. The aim of this study was to construct a valid and reliable multiple‐choice conceptual survey to investigate students’ understanding of introductory quantum physics concepts. We examined course syllabi to establish content coverage, consulted with experts to extract fundamental content areas, and trialled open‐ended questions to determine how the selected content areas align with students’ difficulties. The questions were generated and trialled with different groups of students. Each version of the survey was critiqued by a group of discipline and teaching experts to establish its validity. The survey was administered to 312 students at the University of Sydney. Using the data from this sample, we performed five statistical tests (item difficulty index, item discrimination index, item point biserial coefficient, KR‐21 reliability test, and Ferguson’s delta) to evaluate the test’s reliability and discriminatory power. The result indicates that our survey is a reliable test. This study also provided data from which preliminary findings were drawn on students’ understandings of introductory quantum physics concepts. The main point is that questions which require an understanding of the standard interpretations of quantum physics are more challenging for students than those grouped as non‐interpretative. The division of conceptual questions into interpretive and non‐interpretive needs further exploration.

Chromosome Aberrations as Bioindicators of Environmental Genotoxicity

Due to the exposure to various potentially genotoxic xenobiotics, derived from recent war activities such as NATO air strikes with antitank ammunition containing depleted uranium, we have evaluated chromosome aberrations in 84 peripheral blood samples from three local populations. One population sample included 30 individuals who lived in the Sarajevo area during and after the war (exposed to potential genotoxins), second population was presented with 26 employees of the tank repair facility in Hadzići (target of NATO air strikes), and 28 inhabitants of Posusje (not exposed to war-related activities) were treated as sample of control population. The mean of chromosome aberration frequencies for the population from Hadzići was significantly higher than the frequencies for the two other populations. Point bi-serial coefficient analysis did not reveal any relationship between the frequencies of chromosome aberrations and smoking habits or gender. Results suggest that depleted uranium could be a risk factor for human health.

Breast Ultrasound Computer-Aided Diagnosis Using BI-RADS Features

Based on the definitions in mass category of Breast Imaging Reporting and Data System developed by American College of Radiology, eight computerized features including shape, orientation, margin, lesion boundary, echo pattern, and posterior acoustic feature classes are proposed. Our experimental database consists of 265 pathology-proven cases including 180 benign and 85 malignant masses. The capacity of each proposed feature in differentiating malignant from benign masses was validated by Student's t test and the correlation between each proposed feature and the pathological result was evaluated by point biserial coefficient. Binary logistic regression model was used to relate all proposed features and pathological result as a computer-aided diagnosis (CAD) system. The diagnostic value of each proposed feature in the CAD system was further evaluated by the feature selection methods. Additionally, the likelihood of malignancy for each individual feature was also estimated by binary logistic regression. On each proposed feature, the malignant cases were significantly different from the benign ones. The correlation between the angular characteristic and pathological result was indicated as very high. Three substantial correlations appear in features irregular shape, undulation characteristic, and degree of abrupt interface, but the relationship for orientation feature is low. For the constructed CAD system, the performance indices accuracy, sensitivity, specificity, PPV, and NPV were 91.70% (243 of 265), 90.59% (77 of 85), 92.22% (166 of 180), 84.62% (77 of 91), and 95.40% (166 of 174), respectively, and the area index in the ROC analysis was 0.97. Compared with the significant contribution of angular characteristic, the diagnostic values of posterior acoustic feature and orientation feature were relatively low for the CAD system. When three or more angular characteristics are discovered or the degree of abrupt interface is lower than 18, the likelihood of malignancy could be predicted as greater than 40%. The computerized BI-RADS sonographic features conform to the sign of malignancy in the clinical experience and efficiently help the CAD system to diagnose the mass.

Effect of War and Postwar Genotoxins on Micronuclei Frequency in Sarajevo Study Group

During the 1992-1995 siege, as well as after the war activities, citizens of Sarajevo were most probably exposed to various potential genotoxic agents. The effects of those potential genotoxins were evaluated by micronucleus-cytokinesis blocked assay. The study included 30 individuals who resided in the area of Sarajevo during the war and the postwar period. Point bi-serial coefficient analysis did not reveal any relationship between the frequencies of binuclear cells with micronuclei as well as total number of micronuclei and smoking habits or gender. Simple linear regression revealed statistically significant positive correlation between the age and micronuclei formation. Due to the war related environmental contamination more extensive study is recommended.

Evaluating an electricity and magnetism assessment tool: Brief electricity and magnetism assessment

The Brief Electricity and Magnetism Assessment (BEMA), developed by Chabay and Sherwood, was designed to assess student understanding of basic electricity and magnetism concepts covered in college-level calculus-based introductory physics courses. To evaluate the reliability and discriminatory power of this assessment tool, we performed statistical tests focusing both on item analyses (item difficulty index, item discrimination index, and item point biserial coefficient) and on the entire test (test reliability and Ferguson's delta). The results indicate that BEMA is a reliable assessment tool.

A Structured Clinical Interview for Kleptomania (SCI-K): preliminary validity and reliability testing

Kleptomania presents difficulties in diagnosis for clinicians. This study aimed to develop and test a DSM-IV-based diagnostic instrument for kleptomania. To assess for current kleptomania the Structured Clinical Interview for Kleptomania (SCI-K) was administered to 112 consecutive subjects requesting psychiatric outpatient treatment for a variety of disorders. Reliability and validity were determined. Classification accuracy was examined using the longitudinal course of illness. The SCI-K demonstrated excellent test-retest (Phi coefficient = 0.956 (95% CI = 0.937, 0.970)) and inter-rater reliability (phi coefficient = 0.718 (95% CI = 0.506, 0.848)) in the diagnosis of kleptomania. Concurrent validity was observed with a self-report measure using DSM-IV kleptomania criteria (phi coefficient = 0.769 (95% CI = 0.653, 0.850)). Discriminant validity was observed with a measure of depression (point biserial coefficient = -0.020 (95% CI = -0.205, 0.166)). The SCI-K demonstrated both high sensitivity and specificity based on longitudinal assessment. The SCI-K demonstrated excellent reliability and validity in diagnosing kleptomania in subjects presenting with various psychiatric problems. These findings require replication in larger groups, including non-psychiatric populations, to examine their generalizability.

Biases of success rate differences shown in binomial effect size displays.

The intent of a binomial effect size display (BESD) is to show "the [real-world] importance of [an] effect indexed by a correlation [r]" (R. Rosenthal, 1994, p. 242) by reexpressing this correlation as a success rate difference (SRD) (e.g., treatment group success rate-control group success rate). However, SRDs displayed in BESDs generally overestimate real-world SRDs implied by correlations of (a) dichotomous X and Y variables (phi coefficients), (b) dichotomous X and continuous Y variables (point-biserial coefficients [rpbs]). and (c) continuous X and Y variables (rxys). Furthermore, overestimation biases are larger for rxys than for rpbs. Differences in the sizes of biases linked to different correlations suggest that BESD SRDs reported for different correlations are not comparable. The stochastic difference index (N. Cliff, 1993: A. Vargha & H. D. Delaney, 2000) is recommended as an alternative to the BESD.

A frequent misunderstanding associated with point biserial and phi coefficients.

The label "Pearson r" is legitimately used both for the standard Pearson r calculated on continuous variables and for its other varieties in the form of the point biserial or the phi coefficient. This fact is often ignored by psychologists and psychiatrists.

Lateralized spatial strategies in oscillating drawing movements.

Kinematic characteristics and lateral differences between two upper extremities were investigated in a unimanual graphic task involving fast and precise oscillating movements on the vertical plane. The spatial locations of sequential reversal points were used to calculate the pairs of angles, relative to the horizontal axis. The point biserial coefficient of correlation was used to analyze the difference between big and large angles and their sequence in each pair. Three main groups (A, B, and C) of performance models were distinguished in 132 tests by 33 strongly right-handed male subjects. Group A showed strong variation in vertical movement, Group B covariation in vertical and horizontal vectors, while Group C reflected independent variation of both vertical and horizontal directions. It is suggested that the movement strategies might reflect three different models of motor control involving coupling of an oscillator controlling pools of motoneurons which regulates horizontal movements with an oscillator controlling vertical movement (Groups A + B) or with nonoscillating control signal (Group B). It is argued that Group A represents the simplest strategy and only performance Type A met by the left hand.

Are Schizophrenic Symptoms Different in Patients with Higher Education?

Ratings of 87 symptoms on a Canadian sample of 108 DSM-III schizophrenics (41 men, 67 women) were unrelated (point biserial coefficients) to their education. The only exceptions to this trend were weak correlations with ratings of apathy, insight, and of premorbid adjustment. Patients with higher education were less frequently labelled as apathetic (r = .28) or as lacking insight (r = .26) and their premorbid adjustment was better (r = .25). None of the symptoms traditionally considered as markers specific for schizophrenia was significantly related to education.

Table for Converting the Point Biserial to the Biserial

It is often considerably easier to obtain the value of the point biserial correlation coefficient for a given set of data than it is to obtain the biserial correlation coefficient. A table is presented that directly converts any known point biserial coefficient to the biserial coefficient providing the largest proportion of the dichotomous variable is also known.

Correlation coefficients from 2 × 2 tables and from biserial data

Various measures of correlation between two quantities x and y are discussed, and it is shown that the phi coefficient is a logically unacceptable measure except perhaps when both x and y are purely qualitative two‐valued attributes.For biserial data, a new measure of correlation is proposed which is free from the shortcomings of the biserial coefficient and the point biserial coefficient.

Program package STAP: A statistical appendix

Like many other universities, the University of Amsterdam subscribes to program packages like SPSS and BMDP and also has a collection of self-developed or procured additional stand-alone programs. The latter category is often more up to date than the programs available in packages; however, these programs are often less user-friendly and are often incompatible with the control languages and data structure conventions of the packages. Perhaps differently from other universities, the University of Amsterdam tried to find a solution by the construction of the package STAP. STAP (an acronym for statistical appendix) is not meant to be a new complete package, but, rather, an appendix to SPSS, mainly by providing a number of more advanced statistical procedures in an SPSScompatible way. In the first version of STAP, which is now available, the number of statistical procedures is 13. STAP uses an SPSS-compatible system file with an important modification: As most STAP procedures frequently use matrix input and output, the STAP system file is not only able to contain the raw data but offers matrix input, output, and storage as well. This way, matrices can be passed from one procedure to another within one set-up. Matrices and their functions are indicated by names and key words, minimizing the risk of administrative errors. Other advantages of the modified system file are that (1) other information, such as subfile group, the size of the matrix, and row and column labels, will automatically be stored and retrieved, (2) matrices can be used partially by selecting rows and columns, and (3) full machine precision will be retained. The connection of STAP with SPSS has been realized as follows: STAP uses the same control language as SPSS and contains some data management functions known from SPSS. STAP can read and modify an SPSS system file, and the result can (generally) be read by SPSS. The number of (raw) data management functions in STAP is small; STAP does not even offer the possibility of reading raw data. The user is expected to have done his data management in SPSS, including the creation of a system file. STAP can, without too much difficulty, be extended with new procedures. STAP Procedures and Documentation. The STAP user's manual is contained in seven volumes, each dedicated to more or less related subjects or procedures. Volume I-Volume 1 includes an introduction to STAP (control language, relation STAPISPSS, data definition and management), the STAP Matrix System Guide (the matrix system as an extension of the SPSS system file), a summary (of control cards, etc.), and an appendix (STAP execution within the CDC operating system). Volume 2-Subprogram ASSOCIATION computes covariance, Pearson correlation, point biserial and phi coefficient, biserial phi, biserial correlation, tetrachoric, multiple, and Spearman's rank correlation. Subprogram DlSTANCE computes Minkowski distances measures: the city block, euclidean, and dominance metric. Subprogram CLUSTER performs hierarchical cluster analyses according to (I) Johnson (the maximum and minimum method) and (2) Elshout (based on reciprocity and properties of the correlation coefficient). Volume 3-Subprogram FACAN performs factor analysis as described in Joreskog's (1963) dissertation. Subprogram FACAN SCORES provides estimation of factor scores according to Bartlett, the regression method, and a generalization of the Anderson-Rubin method (see Saris, de Pijper, & Mulder, 1978). Subprogram PROCRUS ROTATE performs procrustean rotation of an orthogonal (factor) matrix toward a target matrix (oblique or orthogonal). Volume 4--Subprograms MOKKEN SCALE and MOKKEN TEST perform stochastic cumulative scaling following Mokken's (1971) model (which is more general than the deterministic Guttman model). Volume 5~Subprogram ITEM ANALYSIS computes the usual test statistics for multiple-choice or attitude and personality inventory tests, with optional information per subject. For attitude scales, the method of Lawshe and Harris is included. Volume 6-Subprogram LINEAR COMB computes the (standardized) linear combinations of scores, which can be added to the system file, Subprogram SCATtER PLOT produces scatter diagrams of data points on a plotter or graphic display. Volume 7~Subprogram NONPAR T-TEST performs Wilcoxon's rank-sum test and Ansari's test for independent samples and Wilcoxon's symmetry test and Spearman's rank correlation coefficient for paired samples. Subprogram NONPAR ONEWAY performs the Kruskal and Wallis rank-sum test for k independent samples, Spjotvoll's contrast estimate between k samples (Hollander & Wolfe, 1973), Steel's range test (Dunn, 1964), Jonckheere and Terpstra's trend test (Hollander & Wolfe, 1973), and Doornbos' (Note 1) test for outliers. The documentation of the procedures contains theoretical introductions, program descriptions, descriptions of the procedure cards, options and statistics, and sample output.

Validation of the CPI Femininity Scale in Romania

The 38-item Fe (Femininity) scale of the California Psychological Inventory has validly differentiated between males and females in several countries. Further cross-cultural study therefore seemed warranted. A Romanian translation was administered to 570 male and 300 female students in high school, engineering school, and college classes in psychology. Means were 17.01 for males and 22.49 for females. The difference of 5.48 was statistically significant (p < .001) and gave rise to a point-biserial coefficient of .58. Of the 38 items, 31 differentiated significantly and in the proper direction; 3 items showed reversals. Analysis of the Masculine and Feminine subscales showed these to be uncorrelated with each other. It was concluded that the Fe scale is sufficiently valid for use in Romanian investigations.