bluuebunny/crossref_metadata_2025 huggingface dataset:
Maximizing Efficiency of Recurrent Phenotypic Selection for Neutral Detergent Fiber Concentration in Smooth Bromegrass
Authors: Stendal C. , Casler M. D.
Published: January 2006

Resources are always limited in plant breeding programs, limiting the number of plots or plants that can be utilized in recurrent selection. Replication of selection units in space or time provides a mechanism to improve the precision of measurements. For smooth bromegrass (Bromus inermis L.), neutral detergent fiber (NDF) is the most effective and measurable predictor of animal intake, a major source of variation for livestock production. The objective of this experiment was to determine the potential benefits and costs of replication in time and space for divergent recurrent selection on NDF of smooth bromegrass. Phenotypic data was used to predict selection response and derive a benefit–cost ratio for a variety of selection criteria based on various numbers of blocks and harvests. Three of the 70 selection criteria examined had an expected selection response significantly greater than that predicted by a log‐linear regression of expected selection response as a function of cost. These selection criteria were based on two or three harvests and one or two blocks. Two of the selection criteria, emphasizing one harvest of unreplicated plants, had a benefit–cost ratio significantly above the mean. If financial resources are not a concern, selection based on the mean of multiple harvests in 1 yr results in the highest expected response per year. If financial resources are greatly limited, one harvest of unreplicated plants provides an adequate expected response per cycle but maximizes gain per unit cost.
Selection for Lodging Resistance in Early Generations of Field Pea by Molecular Markers
Authors: Zhang Chunzhen , Tar'an Bunyamin , Warkentin' Tom , Tullu Abebe , Bett Kirstin E. , Vandenberg Bert , Somers Daryl J.
Published: January 2006

Lodging resistance is a key objective in pea breeding programs. Implementation of marker‐assisted selection (MAS) in early generations could significantly enhance the efficiency of the breeding process compared with conventional selection in the F3 or later generations. The objective of this research was to evaluate the effectiveness of MAS for lodging resistance using a combination of a coupling‐phase linked marker A001 and a repulsion‐phase linked marker A004 in F2 generation field pea (Pisum sativum L.). Eight F2 populations consisting of 680 plants were scored for the markers. A total of 402 F3 families derived from MAS and 187 F3 families from unselected populations were evaluated for lodging reaction under field conditions. The lowest lodging scores for each population were obtained from plants with the combination of A001 marker presence and A004 marker absence. A higher proportion of lodging resistant F3 families was obtained from this marker combination as compared with phenotypic selection in the F3 generation. MAS was less expensive than phenotypic selection in the field. Thus, A001 and A004 are useful for MAS for lodging resistance in early generation pea breeding populations.
Performance of Irrigated Tall Fescue–Legume Communities under Two Grazing Frequencies in the Southern Rocky Mountains, USA
Authors: Lauriault Leonard M. , Guldan Steven J. , Martin Charles A. , VanLeeuwen Dawn M.
Published: January 2006

Irrigated pastures form a significant component of agriculture in the irrigated steppe of the southern Rocky Mountains, USA. Information is limited, however, describing performance of grazed binary perennial cool‐season grass–legume mixtures in the region. Established monoculture tall fescue [Festuca arundinacea Schreb. = Lolium arundinaceum (Schreb.) S.J. Darbyshire] + 134 kg N ha−1 (MONO) and tall fescue mixed with alfalfa (Medicago sativa L.) (ALF/TF), birdsfoot trefoil (Lotus corniculatus L.) (BFT/TF), cicer milkvetch (Astragalus cicer L.) (CM/TF), or kura clover (Trifolium ambiguum M.B.) (KC/TF) at New Mexico State University's Sustainable Agriculture Science Center at Alcalde were subjected to two grazing frequencies (grazed monthly or bimonthly mid‐May to mid‐September) from 1998 to 2000. Grass, legume, and combined dry matter (DM) yields were measured in May 1998 to 2001. A year × grazing frequency × pasture interaction for legume DM yield was moderated by a lack of effect in grass DM yield, leaving a year × pasture interaction for combined DM yield in which MONO, ALF/TF, and CM/TF increased linearly across years and cubic trends were exhibited by ALF/TF and KC/TF. Despite the cubic trend of KC/TF, it and BFT/TF had the most uniform yield distribution across years because of nonsignificant linear effects. Annual combined DM yield averaged 2.21, 3.90, 2.43, 1.93, and 3.03 Mg ha−1 for MONO, ALF/TF, BFT/TF, CM/TF, and KC/TF, respectively, from 1998 to 2001 (5% LSD = 0.77). Kura clover‐tall fescue offers an alternative to alfalfa– tall fescue for long‐term pastures in the irrigated steppe of the southern Rocky Mountains.
Variation of Mucilage in Flax Seed and Its Relationship with Other Seed Characters
Authors: Diederichsen Axel , Raney J. Philip , Duguid Scott D.
Published: January 2006

A four‐location trial in western Canada with 16 North American flax (Linum usitatissimum L.) cultivars was conducted in 2001 and 2002 to investigate the genotypic and environmental influences on mucilage in the flax seed coat. The viscosity of a water extract from intact flax seed was used as quantitative descriptor of the seed‐coat mucilage (mucilage indicator value, MIV). Thousand‐seed weight (TSW) and oil content in the seed were also observed. The MIV in the 16 cultivars ranged from 90.6 to 246.1 centistokes (cSt) mL g−1, TSW ranged from 5.21 to 6.91 g, and oil content ranged from 447 to 491 g kg−1 Significant differences were found among the cultivars for all characters. A screening of 1689 recently regenerated accessions from 61 countries of the Plant Gene Resources of Canada (PGRC) flax collection showed MIVs ranging from 22.1 to 343.4 cSt mL g−1 The ranges for TSW and oil content were 3.53 to 11.50 g and 314 to 457 g kg−1, respectively. The group displaying the highest MIV included registered North American cultivars. There was no association of MIV with geographic origin, TSW, or seed oil content. Recent North American linseed cultivars varied considerably for MIVs, and breeding for this trait without impact on seed oil content or TSW should be possible.
A Cytological Marker Associated with Winterhardiness in Oat
Authors: Santos A. G. , Livingston D. P. , Jellen E. N. , Wooten D. R. , Murphy J. P.
Published: January 2006

The intergenomic translocation T7C‐17 occurs at different frequencies in fall‐ versus spring‐sown hexaploid oat (Avena sp.) germplasm. The objectives of this experiment were to evaluate crown meristem freeze tolerance and winter field survival among 94 random F4–derived lines from the cross between the cultivars Wintok (T7C‐17, winterhardy) and Fulghum (non‐T7C‐17, less winterhardy) and to examine the association between these winterhardiness traits and T7C‐17. Crown meristem freeze tolerance was evaluated in a three‐replicate randomized complete block design in controlled environment growth cabinets. Field survival was evaluated in a three replicate randomized complete block design at Laurel Springs, NC during the 1999–2000 season. Greater crown meristem freeze tolerance and greater winter field survival were associated with the presence of T7C‐17. Lines heterogeneous for the translocation had similar levels of crown meristem freeze tolerance and field survival as lines homozygous for the translocation. Twenty‐two percent of the variation in crown meristem freeze tolerance and 27% of the variation in field survival was accounted for by translocation status. The observed frequencies of translocation homozygotes and heterozygotes did not fit the expected frequencies for single factor segregation in the F4 generation. There were almost threefold as many homozygotes with the translocation as homozygotes without the translocation which indicated preferential selection for T7C‐17 during inbreeding. Our results suggested that T7C‐17 might be isolating, in terms of recombination, either a dominant allele or a group of loci conditioning winterhardiness in our population.
Influence of Grass Species and Sample Preparation on Ensiling Characteristics
Authors: Cherney D. J. R. , Alessi M. A. , Cherney J. H.
Published: January 2006

Laboratory silos are considered a practical method of comparing a number of treatments and are necessary when evaluating numerous experimental variables and their interactions involving different grass silages. Objectives of this study were to evaluate the suitability of grasses ensiled in vacuum‐sealed polyethylene bags to assess treatment differences. Four field replicates of three grass species, orchardgrass (Dactylis glomerata L., OG), reed canarygrass (Phalaris arundinacea L., RG), and tall fescue (Festuca arundinacea Schreb., TF), harvested at two dates were ensiled whole or chopped. Bacterially inoculated grass samples (500 g) were ensiled for 0, 2, 4, 8, 16, 24, or 30 d. At 30‐d post ensiling, lactic acid was the predominant acid, suggesting good fermentation. Differences were noted among species, harvest date, and chop, suggesting that the polyethylene bag is sensitive to treatment differences. There was little or no butyric or propionic acids in the silages, indicating that the silages did not undergo clostridial fermentation. Ensiled grasses dropped rapidly in pH and were stable beyond 4 d for all treatments. Despite species and processing differences, pH of all silages tended to be under 4.7, considered acceptable for grass silages. We conclude that it is possible to use vacuum‐sealed plastic bags to ensile temperate grasses to assess treatment differences.
Conservation and Change: A Comparison of In situ and Ex situ Conservation of Jala Maize Germplasm
Authors: Rice Elizabeth B. , Smith Margaret E. , Mitchell Sharon E. , Kresovich Stephen
Published: January 2006

Conservation of agricultural genetic resources, whether in situ (in farmers' fields) or ex situ (in a germplasm repository), provides variation for breeding and selection efforts. In this study, we assayed levels of genetic diversity from in situ and ex situ populations of Jala, a very tall, large‐eared race of maize (Zea mays L. subsp. mays), using 22 simple sequence repeat (SSR) loci. For comparison, we also analyzed diversity in reference populations of other maize races and wild relatives of maize, the teosintes (both Zea spp. and Z. mays subsp.). As expected, both the in situ and ex situ Jala populations were not as diverse as the teosintes (gene diversity, He, ≈ 0.60 and 0.7, respectively), but they were surprisingly more diverse than the populations representing other maize races (He = 0.55). The older ex situ Jala populations were less diverse and more differentiated than more recently collected accessions. Despite this fact, we observed similar levels of overall genetic diversity in the ex situ and in situ populations (He = 0.62 and 0.61, respectively), and little differentiation between these groups (Fst = 0.01). Therefore, the ex situ Jala collections, as a whole, contained the diversity found today in the field, even though diversity was under‐represented in individual repository populations.
Solving Tangled Cases of Work-Related Musculoskeletal Disorders by International Scientific Cooperation
Authors: Nakata Minori , Ahlgren Christina , From Carin , Lindberg Per
Published: January 2006

Work-related musculoskeletal disorders (WRMSDs) have become a serious worldwide problem. At the same time a number of workers experience a problem in getting their WRMSDs acknowledged. As an attempt to solve these problems, Japanese school lunch cooks' working conditions were discussed at international scientific meetings and a detailed inspection was done at a Japanese school kitchen by Swedish researchers. It revealed that both national and international researchers' opinions coincided. Statements of medical views were written for several tangled cases in Japan and Sweden referring to both the national and international literature. As a result, these tangled cases were acknowledged officially as WRMSDs. New arbitrators and mediators of WRMSDs are required who can understand and communicate between the world of medical and labor sciences and also between the world of science and daily work life.
The Stranded Standard: What Happened to the Proposed ILO Convention on Work in the Fishing Sector?
Authors: Markkanen Pia
Published: January 2006

The 2005 International Labour Conference did not adopt the new proposed Convention on work in the fishing sector. As the whole Employers' Group and a considerable number of government delegates abstained from voting, the quorum was not reached. Workers are disappointed as the Convention aimed at covering more than 90% of the world's fish workers, both in the fields of social security and work environment. Employers described the proposed Convention as prescriptive, inflexible, and impractical for developing countries to ratify it. How much did the Tsunami 2004 influence the result? What kind of standard creation process would suit for the new, globalized world?
Single‐step recovery and solid‐phase refolding of inclusion body proteins using a polycationic purification tag
Authors: Hedhammar My , Alm Tove , Gräslund Torbjörn , Hober Sophia
Published: January 2006

A strategy for purification of inclusion body‐forming proteins is described, in which the positively charged domain Zbasic is used as a fusion partner for capture of denatured proteins on a cation exchange column. It is shown that the purification tag is selective under denaturing conditions. Furthermore, the new strategy for purification of proteins from inclusion bodies is compared with the commonly used method for purification of His6‐tagged inclusion body proteins. Finally, the simple and effective means of target protein capture provided by the Zbasic tag is further successfully explored for solid‐phase refolding. This procedure has the inherited advantage of combining purification and refolding in one step and offers the advantage of eluting the concentrated product in a suitable buffer.
Production of D‐arabitol by a metabolic engineered strain of Bacillus subtilis
Authors: Povelainen Mira , Miasnikov Andrei N.
Published: January 2006

A novel method for D‐arabitol production with a metabolically engineered Bacillus subtilis strain is described. A known transketolase‐deficient and D‐ribose‐producing mutant of B. subtilis (ATCC 31094) was further modified by disruption of its rpi (D‐ribose phosphate isomerase) gene to create a D‐ribulose‐ and D‐xylulose‐producing B. subtilis strain. Expression of the D‐arabitol phosphate dehydrogenase gene of Enterococcus avium in the D‐ribulose‐ and D‐xylulose‐producing strain resulted in a strain of B. subtilis capable of converting D‐glucose to D‐arabitol with a high yield (38%) and little by‐product formation.
Environmental behaviour in Chicago automotive repair micro‐enterprises (MEPs)
Authors: Mir Debby F.
Published: January 2006

This study analyzes the relationship between internal and external factors that influence environmental behaviour in traditional service micro‐enterprises, focusing on Chicago motor vehicle repair (MVR) firms five years after the Clean Break amnesty program and subsequent inspections of MVR firms. The survey explored the influence of firm and manager characteristics, government intervention, and market and social pressures and opportunities on environmental awareness and action. Environmental action was significantly higher in older firms (more experienced owners) and in auto‐refinishing firms practicing spray painting. While awareness levels were mixed for dealerships and franchises (contracted to larger organizations), environmental action was good for six out of the seven firms, which may reflect expectations for higher professional rather than environmental standards. However, environmental awareness and behaviour levels were mixed for trade association members. Owners obtain most environmental information from suppliers and government agencies, but confuse government responsibilities and attribute greater authority to non‐environmental agencies. Finally, micro‐enterprises avoid voluntary environmental compliance programs and prefer targeted enforcement and insurance requirements that promote a level playing field. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Synthesis and Structure—Activity Relationships of 1,2,4‐Triazoles as a Novel Class of Potent Tubulin Polymerization Inhibitors.
Authors: Ouyang Xiaohu , et al. et al.
Published: January 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.
Roots of cube polynomials of median graphs
Authors: Brešar Boštjan , Klavžar Sandi , Škrekovski Riste
Published: January 2006

The cube polynomial c(G,x) of a graph G is defined as $\sum\nolimits_{i \ge 0} {\alpha _i ( G)x^i }$, where αi(G) denotes the number of induced i‐cubes of G, in particular, α0(G) = |V(G)| and α1(G) = |E(G)|. Let G be a median graph. It is proved that every rational zero of c(G,x) is of the form −((t + 1)/t for some integer t > 0 and that c(G,x) always has a real zero in the interval [−2,−1). Moreover, c(G,x) has a p‐multiple zero if and only if G is the Cartesian product of p trees all of the same order. Graphs of acyclic cubical complexes are characterized as the graphs G for which c(H, −2) = 0 holds for every 2‐connected convex subgraph H of G. Median graphs that are Cartesian products are also characterized. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 37–50, 2006
Role of prednisolone treatment in severe Mycoplasma pneumoniae pneumonia in children
Authors: Lee Kyung‐Yil , Lee Hyung‐Shin , Hong Ja‐Hyun , Lee Mi‐Hee , Lee Joon‐Sung , Burgner David , Lee Byung‐Churl
Published: January 2006

Mycoplasma pneumoniae pneumonia (MP) is responsible for 10–40% of cases of pediatric community‐acquired pneumonia. Occasionally, progression to severe pneumonia occurs despite appropriate antibiotic therapy. We retrospectively evaluated the effect of prednisolone in 15 children with MP whose clinical and radiographic course worsened despite broad‐spectrum antibiotics, including appropriate macrolides. The mean ( ± SD) age was 6.1 ± 1.9 years, and 10 were boys. All children had received macrolides at presentation, but they had persistent fever and progressively worsening radiographic findings. In addition to broad‐spectrum antimicrobial therapy, we added prednisolone (1 mg/kg for 3–7 days, then tapered over 7 days) on day 6 (±1.5 days) of admission. Fourteen children became afebrile within 24 hr, and their clinical status and radiographic findings improved over several days. The white blood cell count at presentation was 7,500 ± 2,000/mm3, with a proportion demonstrating lymphopenia (lymphocyte differential, 19.7 ± 5.7%). In conclusion, corticosteroid treatment appeared to be temporally associated with clinical and radiographic improvement, and may be helpful for reducing morbidity in children with macrolide‐nonresponsive severe MP. Further studies may be warranted. Pediatr Pulmonol. © 2006 Wiley‐Liss, Inc.
Effect of a mutation on the structure and dynamics of an α‐helical antifreeze protein in water and ice
Authors: Graether Steffen P. , Slupsky Carolyn M. , Sykes Brian D.
Published: January 2006

One strategy of psychrophilic organisms to survive subzero temperature is to produce antifreeze protein (AFPs), which inhibit the growth of macromolecular ice. To better understand the binding mechanism, the structure and dynamics of several AFPs have been studied by nuclear magnetic resonance (NMR) and X‐ray crystallography. The results have shown that different organisms can use diverse structures (α‐helix, β‐helix, or different globular folds) to achieve the same function. A number of studies have focused on understanding the relationship between the α‐helical structure of fish type I AFP and its function as an inhibitor of ice growth. The results have not explained whether the 90% activity loss caused by the conservative mutation of two threonines to serines (Thr13Ser/Thr24Ser) is attributable to a change in protein structure in solution or in ice. We examine here the structure and dynamics of the winter flounder type I AFP and the mutant Thr13Ser/Thr24Ser in both solution and solid states using a wide range of NMR approaches. Both proteins remain fully α‐helical at all temperatures and in ice, demonstrating that the activity change must therefore not be attributable to changes in the protein fold or dynamics but differences in surface properties. Proteins 2006. © 2006 Wiley‐Liss, Inc.
WHIM Descriptors of Shape
Authors: Gramatica Paola
Published: January 2006

WHIM descriptors are 3D structural descriptors obtained from the (x,y,z)‐atomic coordinates of a molecular conformation of a chemical, and are used successfully in QSAR modelling. They are built in so as to capture relevant 3D information regarding different features of molecular structure: size, shape, symmetry and atom distribution. Different weights are used to obtain particular information for each set of descriptors. Recently, some doubts have been raised in the literature regarding the ability of Weighted Holistic Invariant Molecular (WHIM) descriptors of shape (the K non‐directional WHIM descriptors) to describe the difference between linear and non‐linear molecules. A data set of seventy aliphatic and aromatic chemicals of different shape (linear and branched congeners) has been studied here, and is represented by K descriptors (global non‐directional WHIM descriptors of shape) based on different weights. The K descriptors range from 0 for a spherical molecule to 1 for a perfectly linear molecule. The present study confirms the findings, already reported by the author, that the WHIM descriptors of shape (K) are unequivocally able to differentiate linear and non‐linear molecules.
Item Selection by Means of a Maximizing Function
Authors: Horst Paul
Published: January 2006

A new item selection technique is presented which takes into account the intercorrelations of the items as well as their correlations with the criterion. The technique is regarded as superior to comparable techniques in that it is considered to achieve greater economy of time, greater objectivity of procedure, higher validity, and higher reliability. The mathematical theory underlying the method is developed. An approximate solution of the mathematical equations is suggested. An approximation procedure for the complete item selection technique is presented, based on the mathematical solution, but much simpler in procedure. The clerical operations involved in the approximation procedure are outlined and illustrated on a sample worksheet.
The Determination of Item Difficulty When Chance Success is a Factor
Authors: Guilford J. P.
Published: January 2006

The evaluation of the level of difficulty of a test item is ordinarily derived from the proportion of a specified population passing or failing the item. With items that have a limited number of alternative responses there must be a correction in this proportion to make allowance for chance success. A table of corrected proportions is given for different numbers of alternatives varying from two to eight.
Mathematical Biophysics of Delayed Reflexes in Connection with the Theory of Error Elimination
Authors: Rashevsky N.
Published: January 2006

In continuation of a previous paper, a mechanism of delayed reflexes is considered more in detail. Equations governing such a mechanism are established and approximately solved. The formulae thus obtained describe the phenomenon of “concentration” of a conditioned reflex around a definite time interval after stimulation. Applied along the lines discussed in the previous paper to some simple combinations of stimuli and responses the formulae lead to a description of the elimination of errors by trial. They give a relation between the number of repetitions, necessary to eliminate a wrong act, and other constants, describing the situation.
Comparison of Two Factorial Analyses
Authors: Holzinger Karl J. , Harman Harry H.
Published: January 2006

A Bi-factor analysis is made of Professor Thurstone's battery of fifty-seven tests employing his tetrachoric correlations. Although this analysis is made entirely independent of his multiple factor analysis, a very close agreement is found between the group factors obtained here and Thurstone's verbal descriptions previously published.
Mathematical Biophysics and Psychology
Authors: Rashevsky N.
Published: January 2006

In building a system of mathematical biophysics, as the foundation of which we took the phenomena of cellular multiplication, we have had naturally several occasions to discuss also various physico-mathematical aspects of psychological phenomena. This is not surprising, since the latter forms a prominent branch of general biology. There is, however, still a big difference in our treatment of biophysics of general biology and in the treatment of biophysics of psychology. In the former we started with a rather general concept of a metabolising system and developed therefrom in an almost purely deductive, synthetic way an elaborate abstract theoretical system of biophysics, which incidentally happened to throw interesting light on actual real phenomena of cellular biology. We intentionally underline here the word “incidentally”, to emphasize that, although we consider the development of mathematical biophysics as eventually of greatest importance for the interpretation of empirical biology, we do not consider this “utilitarian” aim as the principal driving motive for our study.
The Bounding Hyperplanes of a Configuration of Traits
Authors: Thurstonb L. L.
Published: January 2006

The purpose of this paper is to describe one of the methods of analyzing a configuration of psychological tests or traits in the problem of isolating primary factors. In factorial analysis a set of traits or tests is represented by a set of radial vectors which are so related to each other that the scalar product of each pair is equal to the corresponding experimentally observed correlation coefficient. Each radial vector represents a trait. The dimensionality of the trait configuration is the rank of the reduced correlational matrix. The reduced correlational matrix has communalities in the diagonal cells.

If there are n trait vectors in the configuration and if the dimensionality is r, then each of the n traits can be described as a linear function, a weighted sum, of any set of r linearly independent vectors. It is assumed here that n > r. These r traits in terms of vchich one may describe or comprehend each of the traits in the configuration have been denoted reference traits.
The Relation between the Difficulty and the Differential Validity of a Test
Authors: Richardson M. W.
Published: January 2006

Using scores of 1200 students on a long test as a criterion, each of five subtests of different difficulty has maximum correlation with the criterion when the criterion is dichotomized at a value appropriate to the difficulty of the subtest. A 50-item test element is scored on an all-or-none basis with different standards for passing, and the percentage of passes for successive points on the criterion variable is computed. The Constant Method is applied to this relationship. The limen thus computed is a measure of difficulty, the dispersion is a measure of average (or total) validity, and the slope of the curve is a measure of differential validity. The difficulty of a test element is thus directly related to the maximum differential validity.
Nomograph for Computing Bi-Serial Correlations
Authors: Dunlap Jack W.
Published: January 2006

The widespread use of bi-serial r in item analysis makes a quick and accurate method of evaluating the formula desirable. Such a method is provided by homographs. Dunlap and Kurtz in their Nomograph No. 47 give a method of solving the better known statement of the formula, namely (1)
The Psychophysics of Mental Test Difficulty
Authors: Guilford J. P.
Published: January 2006

By the use of the Seashore tests of Pitch Discrimination, Intensity Discrimination, Time Discrimination, and the test of Tonal Memory, it is shown that the easiness of an item, as determined by absolute scaling methods, is proportional to the logarithm of the magnitude of the stimulus. It is proposed that this is a case of Fechner's psychophysical law and that the unit of absolute scaling as applied to test items may become a satisfactory unit of all S-scales in the more traditional psychophysical problem.
The Factorial Isolation of Primary Abilities
Authors: Thurstone L. L.
Published: January 2006

This is an experimental study of the isolation, by factor methods, of primary abilities from a battery of tests given to 240 students. The range and nature of the fifty-six tests is briefly described. Tentative interpretations of the twelve orthogonal primary factors are given.
The Theory of the Estimation of Test Reliability
Authors: Kuder G. F. , Richardson M. W.
Published: January 2006

The theoretically best estimate of the reliability coefficient is stated in terms of a precise definition of the equivalence of two forms of a test. Various approximations to this theoretical formula are derived, with reference to several degrees of completeness of information about the test and to special assumptions. The familiar Spearman-Brown Formula is shown to be a special case of the general formulation of the problem of reliability. Reliability coefficients computed in various ways are presented for comparative purposes.
A Machine Method for Computing the Biserial Correlation Coefficient in Item Validation
Authors: Royer Elmer B.
Published: January 2006

A method for computing the biserial correlation coefficients with the aid of punch card equipment is oultined. A numerical example and a work sheet layout is included in the presentation.
A Note on Multidimensional Psychophysical Analysis
Authors: Young Gale , Householder A. S.
Published: January 2006

On viewing Thurstone's psychophysical scale from the point of view of the mathematical theory of one-parameter continuous groups, it is seen that a variety of different psychological or statistical assumptions can all be made to lead to a scale possessing similar properties, though requiring different computational techniques for their determination. The natural extension to multi-dimensional scaling is indicated.
How “G” can Disappear
Authors: Spearman C.
Published: January 2006

In a recent number of this Journal (June, 1941), Professor Guilford has
interestingly called into question the assertion of several authors that
Thurstone’s method of analysis (by maximal frequency of zero
loadings).

“cannot discover a g factor even
when such a factor exists.”

To settle the point, Guilford has submitted to the said analysis a
fictitious factor matrix which was expressly devised to contain
g. The result was that this factor — in
opposition to the assertion mentioned above — did duly make its appearance.
Thereupon he fairly enough proceeds to conclude that:

“a g factor will
not necessarily escape the
analysis”

Not so acceptable, however, is his wide generalization that:

“the problem is typical enough to enable us to predict that
a g factor if present will
usually be discovered.”
A Simple Scoring Weight for Test Items and its Reliability
Authors: Guilford J. P.
Published: January 2006

It is pointed out that the scoring weights for test items should be
approximations to regression-equation weights. For this reason any estimate
of reliability of the weight should not be permitted to influence the size
of the weight but should be used in determining the limit of acceptability
of an item. A simple approximation weight is recommended for general use,
and an abac is provided for the estimation of it
when the correlation between item and criterion is the phi coefficient. A
formula for the standard error of this weight is derived and tables of
significant and very significant weights are presented in terms of
deviations from the median weight.
Further Studies on the Mathematical Theory of Interaction of Individuals in a Social Group
Authors: Rashevsky N.
Published: January 2006

A type of interaction of two active groups is considered, in which the opposition of each group increases as the success of the other increases. Some possible applications of this situation are discussed.
An Analysis of Random and Systematic Changes with Practice
Authors: Greene Edward B.
Published: January 2006

Six motor tests and six nonverbal tests were administered four times to the same subjects. Subjective reports of the subjects are discussed, changes in mean scores and in variability and score correlations from trial to trial are surveyed, and factor analyses of results on the first and fourth trials are presented and compared. Implications of the findings with respect to correction for attenuation are pointed out.
A General Theory of Learning and Conditioning: Part II
Authors: Pitts Walter
Published: January 2006

The second of two parts of this article extends a mathematical theory of non-symbolic learning and conditioning to cases where reward and punishment are involved. The preceding results are generalized to the case where stimuli and responses are related psychophysically, thus constituting a theory of transfer, generalization, and discrimination.
Tables of the Standard Error of Tetrachoric Correlation Coefficient
Authors: Hayes Samuel P.
Published: January 2006

Tables are given for σr√N for the tetrachoric correlation coefficient for the following values of the correlation in the population: .00, ± .10, ± .20, ..., ± .80, ± .90, ± .95.
A Course in the Theory of Mental Tests
Authors: Gulliksen Harold
Published: January 2006

An outline for a course in test theory is presented, together with a list of assignments, problems, and a bibliography. The course has been given in the Psychology Department of the University of Chicago. The material is presented in outline form at the present time because of the increased need for training in test theory due to the increase in the use of psychological tests for classification of military personnel, and because much of the material in such a course must be selected from a wide array of articles in the literature. This material is presented in order that an organized body of material for instructional purposes may be readily available to those interested.
Fundamental Factors of Comprehension in Reading
Authors: Davis Frederick B.
Published: January 2006

A survey of the literature was made to determine the skills involved in reading comprehension that are deemed most important by authorities. Multiple-choice test items were constructed to measure each of nine skills thus identified as basic. The intercorrelations of the nine skill scores were factored, each skill being weighted in the initial matrix roughly in proportion to its importance in reading comprehension, as judged by authorities. The principal components were rather readily interpretable in terms of the initial variables. Individual scores in components I and II are sufficiently reliable to warrant their use for practical purposes, and useful measures of other components could be provided by constructing the required number of additional items. The results also indicate need for workbooks to aid in improving students' use of basic reading skills. The study provides more detailed information regarding the skills measured by the Cooperative Reading Comprehension Tests than has heretofore been provided regarding the skills actually measured by any other widely used reading test. Statistical techniques for estimating the reliability coefficients of individual scores in principal-axes components, for determining whether component variances are greater than would be yielded by chance, and for calculating the significance of the differences between successive component variances are illustrated.
Determination of the Optimum Number of Items to Retain in a Test Measuring a Single Ability
Authors: Bedell B. J.
Published: January 2006

It should be possible to make a test a more accurate measuring instrument by discarding some of the items which have been found, by item analysis, to be inefficient. If this is so, fresh and more reliable scores from the already marked scripts would be obtained by neglecting the discarded items, and, in the future, the abbreviated test would be used. The present article offers two solutions, based on slightly different premises, to the problem of which items to discard when the test has been designed to measure a single ability. In a practical example these yield almost the same result, which is also the result obtained by a less rigorous grouping method described, which is by no means laborious to use.
A Basis for Analyzing Test-Retest Reliability
Authors: Guttman Louis
Published: January 2006

Three sources of variation in experimental results for a test are distinguished: trials, persons, and items. Unreliability is defined only in terms of variation over trials. This definition leads to a more complete analysis than does the conventional one; Spearman's contention is verified that the conventional approach—which was formulated by Yule—introduces unnecessary hypotheses. It is emphasized that at least two trials are necessary to estimate the reliability coefficient. This paper is devoted largely to developing lower bounds to the reliability coefficient that can be computed from but a single trial; these avoid the experimental difficulties of making two independent trials. Six different lower bounds are established, appropriate for different situations. Some of the bounds are easier to compute than are conventional formulas, and all the bounds assume less than do conventional formulas. The terminology used is that of psychological and sociological testing, but the discussion actually provides a general analysis of the reliability of the sum of n variables.
Note on the Scaling of Ratings or Rankings when the Numbers Per Subject are Unequal
Authors: Cureton Edward E.
Published: January 2006

The average rating (or normalized rank) of a person rated by a larger number of judges will in general be closer to the group average than will the average rating of a person rated by a smaller number of judges, as a result of rating unreliability and regression. This note presents a technique for correcting that bias.
A Factorial Study of Fluency in Writing
Authors: Taylor Calvin W.
Published: January 2006

A factorial study of fluency was undertaken to test an hypothesis that at least two fluency abilities would be measured by a battery composed both of word fluency tests used by Thurstone and tests of fluency described by several British investigators. Twenty-eight tests, including ten reference tests for five primary mental abilities, were administered to 181 high-school seniors. Ten centroid factors were extracted, a simple structure was found, and eight factors were interpreted. Five factors defined were the following reference abilities: memory (M), number (N), reasoning (R), verbal comprehension (V), and perceptual speed (P), the last one being somewhat tentatively identified. The main finding is the analysis of fluency into two factors: word fluency (W) and ideational fluency (F). Word fluency is defined as a facility in producing single, isolated words that contain one or more formal restrictions, without reference to the meaning of the words. Ideational fluency is described as a facility in expressing ideas by the use of words and their meanings. Another verbal ability indicated is tentatively interpreted as verbal versatility, the ability to express essentially the same idea by means of several different words or combinations of words.
A Note on the Reflection of Signs in the Extraction of Centroid Factors
Authors: Holley J. W.
Published: January 2006

This note suggests that the reflection of residuals in the centroid method of factor analysis should be continued, whenever possible, after all the sums of the columns in the correlation matrix, excluding diagonal values, are positive. A criterion is given for determining whether further reflection is possible in such cases.
Scale Analysis and the Measurement of Social Attitudes
Authors: Edwards Allen L. , Kilpatrick Franklin P.
Published: January 2006

This paper discusses and compares the methods of attitude scale construction of Thurstone (method of equal-appearing intervals), Likert (method of summated ratings), and Guttman (method of scale analysis), with special emphasis on the latter as one of the most recent and significant contributions to the field. Despite a certain lack of methodological precision, scale analysis provides a means of evaluating the uni-dimensionality of a set of items. If the criteria for uni-dimensionality are met, the interpretation of rank-order scores is made unambiguous, and efficiency of prediction from the set of items is maximized. The Guttman technique, however, provides no satisfactory means of selecting the original set of items for scale analysis. Preliminary studies indicated that both the Likert and the Thurstone methods tend to select scalable sets of items and that their functions in this respect are complementary. A method of combining the Likert and Thurstone methods in order to yield a highly scalable set of items is outlined. Sets of 14 items selected by the method have, in the two cases where the technique has been tried, yielded very satisfactory scalability.
A Rapid Non-Parametric Estimate of Multi-Judge Reliability
Authors: Cartwright Desmond S.
Published: January 2006

A technique is presented for obtaining a rapid estimate of reliability between judges, with special reference to qualitative judgments. It is shown that reliability and discrimination are independent and that estimates of both are needed. A method of obtaining an independent estimate of multi-judge discrimination is developed. It is shown that the size of item-samples is specified by the latter method. Tests of significance for both reliability and discrimination are described.
Optimal Test Length for Maximum Differential Prediction
Authors: Horst Paul
Published: January 2006

For the case of a single criterion a method is already available for determining the optimal distribution of testing time for a battery of predictors, assuming that intercorrelation, validity, and reliability data are available for predictors of arbitrary lengths. In this article a modification and generalization of the method is presented for the case of differential prediction involving a number of criterion variables. A numerical example is given to illustrate the method, after which the mathematical rationale is outlined.
A Method of Scalogram Analysis Using Summary Statistics
Authors: Green Bert F.
Published: January 2006

A method of Guttman scalogram analysis is presented that does not involve sorting and rearranging the entries in the item response matrix. The method requires dichotomous items. Formulas are presented for estimating the reproducibility of the scale and estimating the expected value of the chance reproducibility. An index of consistency is suggested for evaluating the reproducibility. An illustrative example is presented in detail. The logical basis of the method is discussed. Finally, several methods are suggested for dealing with non-dichotomous items.
Maximizing Test Validity by Item Selection
Authors: Webster Harold
Published: January 2006

The exact condition for discarding k items from a test in order to obtain a residual test with higher validity is derived. A proof that validity always increases is given for the case k = 1. The lack of uniqueness of maximum validity when achieved by use of the condition is discussed. With the use of additional restrictions on items to be included in the initial test, a practical test construction procedure which has several advantages over previous methods is developed. The homogeneity of tests constructed by the method is discussed, and applications are given.
Relationships between Two Systems of Factor Analysis
Authors: Harris C. W.
Published: January 2006

Considering only population values, it is shown that the complete set of factors of a correlation matrix with units in the diagonal cells may be transformed into the factors derived by factoring these correlations with communalities in the diagonal cells. When the correlations are regarded as observed values, the common factors derived as a transformation of the complete set of factors of the correlation matrix with units in the diagonal cells satisfy Lawley's requirement for a maximum likelihood solution and are a first approximation to Rao's canonical factors.
Time-Limit Tests: Estimating their Reliability and Degree of Speeding
Authors: Cronbach Lee J. , Warrington W. G.
Published: January 2006

Non-spurious methods are needed for estimating the coefficient of equivalence for speeded tests from single-trial data. Spuriousness in a split-half estimate depends on three conditions; the split-half method may be used if any of these is demonstrated to be absent. A lower-bounds formula, rc, is developed. An empirical trial of this coefficient and other bounds proposed by Gulliksen demonstrates that, for moderately speeded tests, the coefficient of equivalence can be determined approximately from single-trial data. It is proposed that the degree to which tests are speeded be investigated explicitly, and an index τ is advanced to define this concept.
The Variance of the Number of Mutual Choices in sociometry
Authors: Katz Leo , Wilson Thurlow R.
Published: January 2006

The variance of the number of mutual dyads in a sociometric situation where each member of a group chooses independently and at random is derived for unrestricted numbers of choices per group member, as well as for a fixed number of choices. The distribution of the number of mutuals is considered.
Determination of Optimal Test Length to Maximize the Multiple Correlation
Authors: Horst Paul
Published: January 2006

If the lengths of the tests in a battery are altered, their intercorrelations and their validities or correlations with a criterion are also altered. Consequently, the multiple correlation of the battery with the criterion will also be altered. These changes are a function of the reliabilities of the tests. Suppose we have given from a set of experimental data (1) the time allowed for each test in the battery, (2) the reliability of each test, (3) the intercorrelations, and (4) the validities of all the tests. If we specify the over-all testing time we are willing to allow for the test in the future, we can determine the amount by which each test must be altered in order to give the maximum multiple correlation with the criterion. The method is presented, together with numerical examples and the mathematical proof.
Note on the Computation of the Inverse of a Triangular Matrix
Authors: Fruchter Benjamin
Published: January 2006

A simplified method of computing the inverse of a triangular matrix is presented. It is useful with the multiple-group method of factoring the correlation matrix as well as with other factor-analysis and multiple-correlation problems.
A Method of Matrix Analysis of Group Structure
Authors: Luce R. Duncan , Perry Albert D.
Published: January 2006

Matrix methods may be applied to the analysis of experimental data concerning group structure when these data indicate relationships which can be depicted by line diagrams such as sociograms. One may introduce two concepts, n-chain and clique, which have simple relationships to the powers of certain matrices. Using them it is possible to determine the group structure by methods which are both faster and more certain than less systematic methods. This paper describes such a matrix method and applies it to the analysis of practical examples. At several points some unsolved problems in this field are indicated.