bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibrating corneal material model parameters using only inflation data: An ill‐posed problem
Authors: Kok S. , Botha N. , Inglis H. M. 
Published: August 2014

SUMMARYGoldmann applanation tonometry (GAT) is a method used to estimate the intraocular pressure by measuring the indentation resistance of the cornea. A popular approach to investigate the sensitivity of GAT results to material and geometry variations is to perform numerical modelling using the finite element method, for which a calibrated material model is required. These material models are typically calibrated using experimental inflation data by solving an inverse problem. In the inverse problem, the underlying material constitutive behaviour is inferred from the measured macroscopic response (chamber pressure versus apical displacement). In this study, a biomechanically motivated elastic fibre‐reinforced corneal material model is chosen. The inverse problem of calibrating the corneal material model parameters using only experimental inflation data is demonstrated to be ill‐posed, with small variations in the experimental data leading to large differences in the calibrated model parameters. This can result in different groups of researchers, calibrating their material model with the same inflation test data, drawing vastly different conclusions about the effect of material parameters on GAT results. It is further demonstrated that multiple loading scenarios, such as inflation as well as bending, would be required to reliably calibrate such a corneal material model. Copyright © 2014 John Wiley & Sons, Ltd.
Interpreting effect sizes: Toward a quantitative cumulative social psychology
Authors: Stukas Arthur A. , Cumming Geoff 
Published: August 2014

AbstractImproved research practice is based on estimation of effect sizes rather than statistical significance. We discuss the challenging task of interpreting effect sizes in the research context, with particular attention to social psychological research. We emphasize the need to acknowledge the uncertainty in an effect size estimate, as signaled by the confidence interval. Interpretation must consider the independent variables, participants, measures, and other aspects of the research. Comparison with other results in the research field, and consideration of theoretical and practical implications are useful strategies. Researchers should consider the possible value of agreeing on benchmarks to help guide effect size interpretation, at least within focused research fields. More broadly, researchers should wherever possible think of experimental manipulations as well as results in quantitative terms. Doing so is fundamental for designing ingenious, informative experiments, understanding research results and their implications, developing theory, and building a quantitative cumulative social psychology. Copyright © 2014 John Wiley & Sons, Ltd.
Optimization of culturing conditions for toxicity testing with the alga Oophila sp. (Chlorophyceae), an amphibian endosymbiont
Authors: Rodríguez-Gil José Luis , Brain Richard , Baxter Leilan , Ruffell Sarah , McConkey Brendan , Solomon Keith , Hanson Mark 
Published: August 2014

Abstract

Eggs of the yellow-spotted salamander (Ambystoma maculatum) have a symbiotic relationship with green algae. It has been suggested that contaminants that are preferentially toxic to algae, such as herbicides, may impair the symbiont and, hence, indirectly affect the development of the salamander embryo. To enable testing under near-standard conditions for first-tier toxicity screening, the authors isolated the alga from field-collected eggs and identified conditions providing exponential growth rates in the apparent asexual phase of the alga. This approach provided a uniform, single-species culture, facilitating assessment of common toxicity end points and comparison of sensitivity relative to other species. Sequencing of the 18s ribosomal DNA indicated that the isolated alga is closely related to the recently described Oophila amblystomatis but is more similar to other known Chlamydomonas species, suggesting possible biogeographical variability in the genetic identity of the algal symbiont. After a tiered approach to culturing method refinement, a modified Bristol's media with 1 mM NH4+ as nitrogen source was found to provide suitable conditions for toxicity testing at 18 °C and 200 µmol m−2 s−1 photosynthetically active radiation (PAR) on a 24-h light cycle. The validity of the approach was demonstrated with Zn2+ as a reference toxicant. Overall, the present study shows that screening for direct effects of contaminants on the algal symbiont without the presence of the host salamander is possible under certain laboratory conditions. Environ Toxicol Chem 2014;33:2566–2575. © 2014 SETAC
Busy tone‐based channel access control for cooperative communication
Authors: Xie Kun , Xie Kexin , He Shiming , Zhang Daqiang , Wen Jigang , Lloret Jaime 
Published: August 2014

AbstractCooperative communication has attracted many research interests in recent years because it can take advantage of the broadcast nature of wireless communications and spatial diversity to improve the network performance. Although relay nodes in cooperative communications can help improve the performance, relay nodes may cause the serious competition on wireless channel accessing, which makes the channel access problem in cooperative communications challenging. To solve this problem, based on cooperative triple busy tone multiple access, this paper proposes a media access control scheme that concurrently combines the request to send/clear to send and busy tone with a proper tone duration timer. In the scheme, three busy tones are proposed to coordinate the nodes in the network to transmit packets, which is further utilised to solve the hidden terminal and exposed terminal problems in cooperative communications. Among the three busy tones, the cooperative busy tone is set according to the relay's signal‐to‐noise ratio. Based on the busy tone, this paper also proposes a bandwidth efficient relay selection algorithm, in which the source node can select the best relay in a distributed way by monitoring the busy tone. The simulation results demonstrate that the proposed scheme can largely reduce the blocking time and improve the channel utilisation in wireless cooperative networks. Copyright © 2014 John Wiley & Sons, Ltd.
PREDICTION OF SECOND‐YEAR GRADE‐POINT AVERAGES AT THE U. S. NAVAL POSTGRADUATE SCHOOL
Authors: Mollenkopf William G. 
Published: August 2014

ABSTRACTIn July 1948 twenty aptitude and achievement tests were given to members of the incoming class at the Naval Postgraduate School. These tests, previously validated against the criterion of first‐year quality‐point ratios, have now been correlated with grade data for the first two terms of the second year at the School. Scores on all of the tests previously found to have high effectiveness for predicting first‐year academic performance were found to be significantly related to second‐year grades. Using a technique developed by Horst, an estimate of .43 was obtained for the value of the multiple correlation between tests and criterion.Since the second‐year validities were consistently and appreciably lower than those for the first year, various possible explanations for the decreases in validity from first to second year were suggested and examined. It was concluded that part of this decrease was due to an observed lower reliability for second‐year grades, and that part was due to the effects of selective drop‐out. It was also concluded that in part this decrease was due to differences between the first‐ and second‐year curricula (with abilities required for success in the second year which were perhaps not measured as well by the tests as the abilities required for success in the first year), and to real changes which might have occurred in the students during the elapsed time interval, for example, changes in motivation.Since several of these factors which tend to reduce the test‐criterion are in no way faults of the tests, it was concluded that the second‐year validities may be regarded as fairly satisfactory. However, further work in the area seems desirable.
AN INVESTIGATION OF THE PROBLEM OF CORRECTION FOR GUESSING
Authors: Keats John A. 
Published: August 2014

ABSTRACTThe purpose of this bulletin is to set out a method of investigating the problem of correction for guessing. The method involves the use of probability theory and a model which may be made more or less complicated. Methods of estimation are set out under certain assumptions, including an estimate of the average probability of success by guessing for a given group of persons and items. Data are collected by repeated testing. Illustration data and a list of problems which should be investigated are presented.
ON THE STABILITY OF PSYCHOLOGICAL MEASURES
Authors: Saunders David R. 
Published: August 2014

ABSTRACTThe stability of a measured psychological function may be assessed by comparing the scores obtained by the same subjects on two or more separate occasions. Three observable effects of instability on the score distribution are (i) change in the mean, (ii) change in the variance, and (iii) change in the ranking, i.e., lack of perfect retest correlations even after proper attenuation corrections. This report is concerned with methods for summarizing, displaying and accounting for large quantities of such data, for a variety of age‐levels and time‐spans.Changes in mean may be readily plotted against age or time, and associated with the average growth of the group. Changes in variance may be readily plotted, but do not have any very useful interpretation. Changes in ranking cannot be directly plotted except by introducing an arbitrary anchor point in the time scale; a series of plots is required to cover all the data.Changes of variance and ranking may be jointly transformed into two other functions: (i) the rate, s, at which “new” variance is entering the quantity measured within the group of subjects, and (ii) the correlation, q, of this “new” variance with the scores that already exist at the same age (or time). Conceptually, these functions depend on instantaneous values of age (or time) so that each is readily plotted as a single curve; yet any retest correlation in the range of the original data may be estimated from the two plots.Actual data to illustrate the scope of this approach are not available. A partial illustration is afforded by Strong's data for the “Interest‐Maturity Scale,” for which a step‐function approximating s is obtained under the main assumption that q is constantly zero. The interpretation of these and other possible results is discussed.
ESTIMATION OF PARAMETERS FROM INCOMPLETE DATA
Authors: Lord Frederic M. 
Published: August 2014

ABSTRACTMaximum likelihood estimators are found for the parameters of a normal trivariate population in the case where observations on one variable are missing from part of the data and observations on another variable are missing from the remainder of the data. Results are presented showing the amount of additional information obtained by these maximum likelihood methods, which make optimum use of the fragmentary data. She formulas derived may also be applied to fragmentary bivariate data.
A SURVEY OF ACTUAL TEST‐SCORE DISTRIBUTIONS WITH RESPECT TO SKEWNESS AND KURTOSIS*
Authors: Lord Frederic M. 
Published: August 2014

ABSTRACTA survey of 48 different aptitude and achievement tests administered to various populations shows that (a) the easier tests tend to have negatively skewed, and the more difficult tests positively skewed, score distributions; (b) most of the score distributions are at least slightly platykurtic, some of them distinctly so.
ACADEMIC PERFORMANCE OF PUBLIC AND PRIVATE SCHOOL GRADUATES AT PRINCETON
Authors: Davis Junius A. , Frederiksen Norman 
Published: August 2014

ABSTRACTThe regressions of average grade in liberal arts at Princeton on ability measures were compared for graduates of public and private schools. Public school graduates were found to be superior to private school graduates in freshman average grade when ability as measured by SAT‐V is taken into account. The public school graduates were also found to be superior with respect to sophomore average when ability is taken into account, whether ability is measured by first‐term average grade, the Converted School Grade, SAT‐V, or a combination of first‐term average with Converted School Grade. Freshman grades can be predicted somewhat more accurately by separate consideration of public and private school graduates. Abacs are described which provide an easy graphical method for translating scores on ability measures into predicted grades.
SOME PERSPECTIVES ON “THE ATTENUATION PARADOX IN TEST THEORY”
Authors: Lord Frederic M. 
Published: August 2014

ABSTRACTFour points relating to Dr. Loevinger's “attenuation paradox” have “been brought forward:

The usual product‐moment “validity” coefficient is inadequate for any discussion of the paradox. A curvilinear correlation coefficient must be used. The “region of paradox” is still found when the correct coefficient is used, although its size is reduced.
A greatly magnified notion of the extent to which the “paradox” occurs in actual achievement and aptitude testing is frequently encountered. Some numerical values are tabled so as to clarify this point.
It is pointed out that any over‐all “validity” coefficient for a group of examinees can be no more than an average of heterogeneous information. It is not surprising if this inhomogeneity produces so‐called paradoxes. Such a composite coefficient is not basic to psycho‐metrics. The discriminating power of the test for a specified decision problem regarding a specified examinee is the truly basic concept. A very simple index for describing this discriminating power is defined.
One instance where a consideration of the discriminating power of a test at a particular ability level leads to some practical conclusions (irrespective of the “region of paradox”) is mentioned, and a common misconception is corrected. A table is given showing the optimum item‐difficulty level for the peaked tests required when the examiner's purpose is merely to classify a group of examinees as successful or unsuccessful.
THE ESTIMATION OF NONSPURIOUS CORRELATIONS
Authors: Angoff William H. 
Published: August 2014

ABSTRACTA method is provided for estimating the nonspurious correlation of a part of a test with the total test in which it is included by considering a hypothetical “subtest”, parallel to the actual subtest but separate from the total test, and determining its correlation with the total test. Two cases are considered: one in which the actual subtest is parallel to the total test, and the other, in which the actual subtest is not parallel to the total test. Data are given to illustrate the applicability of the formulas.
A FACTOR ANALYSIS OF MEMORY ABILITY
Authors: Kelley H. Paul 
Published: August 2014

ABSTRACTThe purpose of this study is to investigate the area in the memory domain concerning relatively immediate intentional retention. For memory tests limited to this area, is there a general memory factor; if not, can several distinct memory factors be identified?On the basis of hypotheses regarding the nature of four memory factors, a battery of 27 memory tests was constructed. These tests, together with 13 reference tests, were administered to 442 pilot cadets at Lackland Air Force Base, San Antonio, Texas. The scores on the 40 tests were then intercorrelated and factor‐analyzed. The multiple‐grouping method of analysis was used, with the solution being iterated twice; the resulting factor matrix was then rotated to oblique simple structure.Eleven factors were found, three of which are rather clearly‐defined memory factors; they may be called Rote Memory, Meaningful Memory, and Span Memory. The reference tests clearly identify three other factors as Verbal Comprehension, Numerical Facility, and Perceptual Speed. The seventh factor is a doublet representing the specific variance of two parallel tests. The eighth factor is a triplet which cannot be positively identified. The remaining three factors all primarily seem to involve visual tasks. These factors seem to represent Visualization, Spatial Relations, and Visual Memory, but the identifications are uncertain since there seems to be confounding with Deductive Reasoning and Psychomotor Coordination.It has been established that in the area of immediate intentional retention there is no general factor; three distinct factors in this domain were clearly identified, while still others were suggested. The three memory factors found seem to be differentiated in terms of process rather than in terms of content or mode of presentation.
NOTE ON A NON‐PARAMETRIC TEST FOR CORRELATION FOR DATA EXPRESSED IN THE FORM OF RANK ORDERS WITHIN SUBGROUPS
Authors: Torgerson Warren S. 
Published: August 2014

ABSTRACTKendall's rank order test for association between two variables is generalized to the case where the total sample is made up of several subgroups and the data on one or both variables consist of the rank order within each subgroup. The test involves no assumptions concerning scales of measurement, shapes of distributions, or relative level of excellence or amount of variability of the different subgroups. Two empirical examples indicate that the normal approximation to the exact test of significance can be considered adequate for most practical situations. Special consideration is given to the case of tied ranks. If ties occur in but one variable within any given subgroup, only a slight modification in procedure is needed. Extensive ties in both variables within subgroups lead to difficulties in determining the appropriate correction for continuity.
ESTIMATING TEST RELIABILITY
Authors: Lord Frederic M. 
Published: August 2014

ABSTRACTFormulas for parallel‐form reliability coefficients are derived from two improved definitions of parallelism. One definition, based on randomly parallel test forms, leads to a new and useful derivation for the KR formula‐21 coefficient. The other, based on matched test forms, leads to a formula for the least upper bound of the test reliability. A numerical example is given, showing how a standard error of measurement for each separate examinee is readily computed, and how the test reliability may be computed by averaging these standard errors.
DETERMINATION OF PARAMETERS OF A FUNCTIONAL RELATION BY FACTOR ANALYSIS*
Authors: Tucker Ledyard R 
Published: August 2014

ABSTRACTConsideration is given to determination of parameters of a functional relation between two variables by the means of factor analysis techniques. If the function can be separated into a sum of products of functions of the individual parameters and corresponding functions of the independent variable, particular values of the functions of the parameters and of the functions of the independent variables might be found by factor analysis. Otherwise approximate solutions may be determined. These solutions may represent important results from experimental investigations.
A TEST OF THE SIGNIFICANCE OF DIFFERENCE BETWEEN CORRELATED PROPORTIONS
Authors: Keats John A. 
Published: August 2014

ABSTRACTThis bulletin reports a likelihood ratio test of the significance of the difference between correlated proportions developed by Dr. S.S. Wilks. A test of the independence of the variables yielding these proportions on the assumption of equal difficulty is also presented. It is also shown that the tests of the significance of differences between correlated proportions used in the literature are in fact ways of estimating a conditional probability. Computational formulae and a computational layout as well as an illustrative example are included.
FACTOR STUDY OF THE SELECTIVE SERVICE COLLEGE QUALIFICATION TEST
Authors: French John W. 
Published: August 2014

ABSTRACTOne form of the Selective Service College Qualification Test was given to first‐year cadets at West Point in May 1951. Six subscores of the test and the total test score were added to a factor analysis of Comparative Prediction tests which had already been carried out with the same class of cadets as subjects. Loadings were obtained for the SSCQT scores on the 16 factors obtained for the Comparative Prediction tests. The SSCQT was found to be mostly verbal with very little saturation on the Mathematics factor. There was evidence that the slow, careful students did better on the test than those standing low on the carefulness factor and high on perceptual speed.
INFERRING THE SHAPE OF THE FREQUENCY DISTRIBUTION OF TRUE SCORES AND OF ERRORS OF MEASUREMENT
Authors: Lord Frederic M. 
Published: August 2014

ABSTRACTGiven k parallel, fallible measures on each individual in a group, all the multivariate cumulants of k ‐th and lover orders for the joint distribution of true scores and errors of measurement may be expressed as simple linear functions of the multivariate cumulants of the fallible measures. It is assumed only that the number of examinees is large; that over a very large number of different testings, the average error of measurement will be zero for each examinee; and that the errors of measurement for two different examinees, or for two different testings of the same examinee, are independently distributed. The form of the frequency distribution of the errors is unspecified and may be different for different individuals. The results of a numerical application to psychological test data are given.
INTERPRETING COLLEGE GRADE AVERAGES
Authors: Ward Lewis B. 
Published: August 2014

ABSTRACTThe records of students attending the Graduate School of Business Administration of Harvard University illustrate the fact that students with similar undergraduate grade records from different colleges often achieve consistently different levels of academic performance in Graduate School. When based on samples of ten or more, these differences in relative performance are surprisingly stable from one four‐year period to another. The substantial correlation between the size and direction of such differences and average scores of other students from these same colleges on admissions tests for law and medical schools suggests that the differences reflect characteristic institutional differences in the sampling of general academic ability which remain stable over long periods and across many different fields of interest. The common belief that grades from certain colleges predict the future graduate school performance of their students relative to each other more consistently than do grades from other colleges is not substantiated by the data where the size of sample is at least 10 per college.
RESPONSE SETS AND GRADES1
Authors: Hills John R. , Raine Walter J. 
Published: August 2014

SUMMARYPursuing earlier results which indicated that response‐set scores might be important predictors of grades in law schools, data from four more schools were obtained and analyzed. These data suggest that while response sets may be useful predictors, they are subject to certain important restrictions. First, response sets do not seem to be effective when ability variables are already doing the job well. Second, a set cannot operate as a predictor if it scarcely exists in the inventory‐taking behavior of the students. The latter restriction might be overcome by allowing or encouraging students to display the set more extensively. What particular kind of set will be helpful in predicting grades in a particular school may sometimes be forecast by someone who knows the school well.