Ability Estimates Research Articles

Using Rasch Analysis to Assess and Improve the Measurement Properties of a Questionnaire With Few Items: The York Binaural Hearing-Related Quality of Life (YBHRQL) Questionnaire.

The York Binaural Hearing-Related Quality of Life questionnaire is a condition-specific preference-based instrument sensitive to advantages of binaural over monaural hearing. Respondents use 5-point scales to report the difficulty experienced with three dimensions of listening that are easier or more successful when hearing is binaural: understanding speech in spatially separated noise, localizing sources of sound in azimuth, and the associated effort and fatigue. Previously, a preference value was estimated for each combination of dimension and level so that a value of binaural utility could be assigned to a respondent to inform analyses of cost effectiveness. The present objective was to determine whether the questionnaire conforms with the Rasch model sufficiently well for estimates of the binaural abilities of respondents to be obtained on an interval scale to inform parametric analyses of clinical effectiveness. Data were obtained from unilateral cochlear implantees (N = 418; 209 ≤62 years; 209 ≥63 years) and members of the public (N = 325; 207 ≤62 years; 118 ≥63 years). A subset of implantees (N = 118) responded at test and retest. Responses were fitted to the partial credit model using the Extended Rasch Modeling package. Conformity with the model was evaluated in six ways: the ordering of response categories ( Monotonicity ) was assessed with plots of response probability against ability; differential item functioning ( DIF ) was assessed by analyses of variance of standardized response residuals; alignment of participants' abilities with item difficulties ( Targeting ) was assessed with person-item maps; fit to the model ( Fit ) was assessed by comparing the means and variabilities of observed and expected responses, and by comparing observed values with analyses of simulated datasets; the hypothesis that item difficulties and participants' abilities were measured on a single underlying scale ( Unidimensionality ) was assessed with principal components analyses of standardized response residuals. Values of fit statistics were toward the lower end of the acceptable range. Comparisons with analyses of simulated datasets showed that low values were primarily the result of the structural limitation of including only three items. Modal values of the probabilities of response categories were ordered monotonically, but some response thresholds were disordered because of under-use of one category. Pooling categories to correct disordered thresholds resulted in estimates of ability that were less discriminatory of differences within and between groups, and showed less reproducibility between test and retest, than did the original estimates. Neither source-related DIF nor gender-related DIF arose. Uniform age-related DIF arose for the speech-in-noise item and could be managed by resolving the item. The resulting estimates of ability and difficulty were well targeted and unidimensional. The York Binaural Hearing-Related Quality of Life questionnaire, with three items each with five response categories, conforms with the Rasch model sufficiently well to yield practically useful measures of the abilities of participants. The trait measured by the questionnaire aligns with the ability to benefit from binaural hearing. More discriminatory measurement of this ability would be achieved with more items. Nonetheless, the questionnaire possesses the virtue that responses to the same three questions can be scored in different ways to inform parametric analyses of both cost-effectiveness and clinical effectiveness.

Should Intelligence Tests Be Speeded or Unspeeded? A Brief Review of the Effects of Time Pressure on Response Processes and an Experimental Study with Raven's Matrices.

Intelligence tests are often performed under time constraints for practical reasons, but the effects of time pressure on reasoning performance are poorly understood. The first part of this work provides a brief review of major expected effects of time pressure, which includes forcing participants to skip items, convoking a mental speed factor, constraining response times, qualitatively altering cognitive processing, affecting anxiety and motivation, and interacting with individual differences. The second part presents data collected with Raven's matrices under three conditions of speededness to provide further insight into the complex effects of time pressure, with three major findings. First, even mild time pressure (with enough time available for all participants to complete the task at a leisurely pace) induced speeding throughout the whole task, starting with the very first item, and participants sped up more than was actually required. Second, time pressure came with lower confidence and poorer strategy use and a substantial decrease of accuracy (d = 0.35), even when controlling for response time at the item level-indicating a detrimental effect on cognitive processing beyond speeding. Third, time pressure disproportionately reduced response times for difficult items and participants with high ability, working memory capacity, or need for cognition, although this did not differentially affect ability estimates. Overall, both the review and empirical sections show that the effects of time pressure go well beyond forcing participants to speed or skip the last few items and make even mild time constraints inadvisable when attempting to measure maximal performance, especially for high-performing samples.

Face identification proficiency test designed using item response theory.

Measures of face-identification proficiency are essential to ensure accurate and consistent performance by professional forensic face examiners and others who perform face-identification tasks in applied scenarios. Current proficiency tests rely on static sets of stimulus items and so cannot be administered validly to the same individual multiple times. To create a proficiency test, a large number of items of "known" difficulty must be assembled. Multiple tests of equal difficulty can be constructed then using subsets of items. We introduce the Triad Identity Matching (TIM) test and evaluate it using item response theory (IRT). Participants view face-image "triads" (N = 225) (two images of one identity, one image of a different identity) and select the different identity. In Experiment3, university students (N = 197) showed wide-ranging accuracy on the TIM test, and IRT modeling demonstrated that the TIM items span various difficulty levels. In Experiment3, we used IRT-based item metrics to partition the test into subsets of specific difficulties. Simulations showed that subsets of the TIM items yielded reliable estimates of subject ability. In Experiments3a and b, we found that the student-derived IRT model reliably evaluated the ability of non-student participants and that ability generalized across different test sessions. In Experiment3c, we show that TIM test performance correlates with other common face-recognition tests. In summary, the TIM test provides a starting point for developing a framework that is flexible and calibrated to measure proficiency across various ability levels (e.g., professionals or populations with face-processing deficits).

Estimation of physiologic ability and surgical stress (E-PASS) predicts postoperative major complications after hepato-pancreato biliary surgery in the elderly

Estimation of physiologic ability and surgical stress (E-PASS) predicts postoperative major complications after hepato-pancreato biliary surgery in the elderly

The prognostic ability of immune scoring system Immunoscore in patients with localized colon cancer: A systematic review and meta-analysis.

2565 Background: Assessment of tumor recurrence risk as well as prognosis in resectable colon cancer are still mainly based on the histopathological criteria of tumor invasion reflected in the TNM classification. Robust data in colorectal tumor research show the value of tumor microenvironment and tumor‐infiltrating lymphocytes (TILs) as novel parameters to predict recurrence and survival. The utility of the derived tumor Immunoscore via digital pathology is now being promoted to refine the prognosis of early colon cancer patients together with the TNM staging to guide treatment decisions, but is not yet a recommendation in international consensus guidelines. This study assessed the prognostic value of this diagnostic tool in predicting clinical outcomes. Methods: A systematic literature search using PubMed, Embase, and Cochrane CENTRAL Library was conducted to identify observational or randomized controlled studies from January 2008 and December 2022 according to pre- specified inclusion and exclusion criteria which examined the relationship between Immunoscore and long-term prognosis (overall survival and disease free survival) in patients with localized colon cancer. Hazard ratios with 95% confidence interval for overall survival (OS) and disease-free survival (DFS) were extracted. Pooled estimates of the prognostic ability of Immunoscore were obtained using bi-variate random effects model. Statistical heterogeneity between studies was evaluated with I2 statistics and explored through sensitivity analysis. Results: A total of 5,718 patients from 11 studies were included in the meta-analysis. Moderate heterogeneity between studies for both DFS (I2= 27%) and OS (I2= 33%) was seen. The pooled analysis indicated that compared to those with high Immunoscore, colon cancer patients with low Immunoscore were associated with shorter disease-free survival (HR 1.75, 95% CI 1.53 - 2.49) and overall survival (HR 1.87 95% CI 1.45 – 2.13). In the subgroup analyses, this association was consistent across geographic regions and maximum time of follow up. Conclusions: A low Immunoscore was significantly associated with poorer clinical outcomes in terms of disease-free survival and overall survival. The use of Immunoscore provides valuable estimate of the risk of recurrence in patients with early colon cancer and has the potential to greatly affect treatment decisions in conjunction with the existing risk assessment system.

A sequential Bayesian changepoint detection procedure for aberrant behaviours in computerized testing.

Changepoints are abrupt variations in a sequence of data in statistical inference. In educational and psychological assessments, it is essential to properly differentiate examinees' aberrant behaviours from solution behaviour to ensure test reliability and validity. In this paper, we propose a sequential Bayesian changepoint detection algorithm to monitor the locations of changepoints for response times in real time and, subsequently, further identify types of aberrant behaviours in conjunction with response patterns. Two simulation studies were conducted to investigate the efficiency and accuracy of the proposed detection procedure in terms of identifying one or multiple changepoints at different locations. In addition to manipulating the number and locations of changepoints, two types of aberrant behaviours were also considered: rapid guessing behaviour and cheating behaviour. Simulation results indicate that ability estimates could be improved after removing responses from aberrant behaviours identified by our approach. Two empirical examples were analysed to illustrate the application of the proposed sequential Bayesian changepoint detection procedure.

Selection of parents and segregating populations of carioca common bean resistant to Fusarium wilt

Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) is one of the most common diseases in the common bean (Phaseolus vulgaris) crop, and the most viable alternative for its control is the use of resistant cultivars. However, the number of “carioca” cultivars, the most important commercial group in Brazil, which has a good level of resistance to this disease, is still low. To obtain populations with a higher degree of resistance, seven parents with different levels of resistance to Fusarium and which produce carioca grains were crossed in a complete diallel design. The 21 segregating populations obtained were evaluated in the years/generations 2012/F3, 2013/F4, and 2014/F5 in experiments in Santo Antônio de Goiás, GO, in the winter crop season (sowing in May), together with the check cultivars BRS Notável (resistant) and BRS Cometa (susceptible) in an area naturally infested with Fusarium oxysporum f. sp. phaseoli, under a center pivot irrigation system. Reaction to Fusarium wilt, yield, and 100-seed weight were evaluated. Additive and non-additive effects contributed to control of reaction to Fusarium wilt, yield, and 100-seed weight. The statistically negative general combining ability ( ) estimates for BRS Notável (-0.51), CNFC 15872 (-0.20), IPR Juriti (-0.18), and BRSMG Talismã (-0.13) indicate that these parents are recommended for obtaining populations more resistant to Fusarium wilt. Among them, cultivar BRS Notável also showed a statistically positive estimate for grain yield (87.90). Among the parents recommended for resistance to Fusarium wilt, cultivars IPR Juriti (0.99) and BRS Notável (0.23) are those that most contributed to obtaining populations with larger-sized beans. Cultivar BRS Notável is the most promising parent for participation in new crossing blocks, showing non-zero estimates for all traits, favoring an increase in resistance to Fusarium wilt, yield, and 100-seed weight. Populations BRS Notável / CNFC 15872, BRS Ametista / BRS Notável, BRS Notável / BRSMG Talismã, and BRS Ametista / BRSMG Talismã showed good mean values for reaction to Fusarium wilt, yield, and 100-seed weight and at least one parent with a good general combining ability estimate for resistance to Fusarium wilt. These four populations are promising for obtaining lines with superior performance for resistance to Fusarium wilt, yield, and larger-sized grains.

Place and immigrant labour market integration: A sequence analysis approach

Although the process of integrating immigrants into the labor market unfolds over many years, it is often modeled as outcomes (e.g. employment) at specific points in time. We contribute to the literature by providing empirical evidence of the sequence of events leading to active labor market participation of East African and EU15 immigrants to Sweden, whom we follow for up to 28 years. By combining the method of sequence analysis with binomial logit estimation, we can explain why individuals are sorted into different representative labor market sequences. A further contribution is that along the usual initial conditions (individual and geographic), we employ longitudinal micro data to find (1) representative sequences of movements between various types of neighborhoods and (2) an empirical estimate of individual ability, which turns out to be a strong predictor for immigrants entering an active labor market trajectory. Our results show that East Africans tend to reside in neighborhoods with a high degree of socioeconomic and ethnic segregation. Despite this, their labor market activity seems to be less influenced by neighborhood trajectories than EU15 immigrants. The labor market activity of EU15 immigrants and female East African immigrants is positively related to residing in less ethnically segregated and socioeconomically stronger neighborhoods. Our results are relevant to policy development since they point to the importance of the initial location of immigrants and their subsequent residential mobility.

Clinical usability of the Story-Based Empathy Task (SET) in non-demented ALS patients.

This study aimed at assessing the clinical usability of the Story-Based Empathy Task (SET) in non-demented amyotrophic lateral sclerosis (ALS) patients. N = 106 non-demented ALS patients and N = 101 healthy controls (HCs) were administered the SET, which includes three subtests assessing Emotion Attribution (SET-EA), Intention Attribution (SET-IA) and causal inference (SET-CI) - the latter being a control task. Patients also underwent the Reading the Mind in the Eyes Test (RMET), the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) and a thorough behavioural and motor-functional evaluation. The diagnostics of the SET-EA and -IA were tested against a defective performance on the RMET. The association between SET subtests and cognitive/behavioural outcomes was examined net of demographic and motor-functional confounders. Case-control discrimination was explored for each SET subtest. Demographically adjusted SET-EA and -IA scoresaccurately detected defective RMET performances at the optimal cutoffs of <3.04 (AUC = .84) and <3.61 (AUC = .88), respectively. By contrast, the SET-CI performed poorly in doing so (AUC = .58). The SET-EA converged with the RMET, as well as with ECAS-Executive and -Memory scores, whilst the SET-IA was unrelated to cognitive measures (including the RMET); the SET-CI was related to the ECAS-Language the ECAS-Executive. SET subscores were unrelated to behavioural outcomes. Only the SET-EA discriminated patients from HCs. The SET as a whole should not be addressed as a social-cognitive measure in this population. At variance, its subtest tapping on emotional processing - i.e., the SET-EA - is recommended for use as an estimate of social-cognitive abilities in non-demented ALS patients.

Accuracy of Naming Error Profiles Elicited From Adaptive Short Forms of the Philadelphia Naming Test.

The purpose of this study was to evaluate whether a short-form computerized adaptive testing (CAT) version of the Philadelphia Naming Test (PNT) provides error profiles and model-based estimates of semantic and phonological processing that agree with the full test. Twenty-four persons with aphasia took the PNT-CAT and the full version of the PNT (hereinafter referred to as the "full PNT") at least 2 weeks apart. The PNT-CAT proceeded in two stages: (a) the PNT-CAT30, in which 30 items were selected to match the evolving ability estimate with the goal of producing a 50% error rate, and (b) the PNT-CAT60, in which an additional 30 items were selected to produce a 75% error rate. Agreement was evaluated in terms of the root-mean-square deviation of the response-type proportions and, for individual response types, in terms of agreement coefficients and bias. We also evaluated agreement and bias for estimates of semantic and phonological processing derived from the semantic-phonological interactive two-step model (SP model) of word production. The results suggested that agreement was poorest for semantic, formal, mixed, and unrelated errors, all of which were underestimated by the short forms. Better agreement was observed for correct and nonword responses. SP model weights estimated by the short forms demonstrated no substantial bias but generally inadequate agreement with the full PNT, which itself showed acceptable test-retest reliability for SP model weights and all response types except for formal errors. Results suggest that the PNT-CAT30 and the PNT-CAT60 are generally inadequate for generating naming error profiles or model-derived estimates of semantic and phonological processing ability. Post hoc analyses suggested that increasing the number of stimuli available in the CAT item bank may improve the utility of adaptive short forms for generating error profiles, but the underlying theory also suggests that there are limitations to this approach based on a unidimensional measurement model. https://doi.org/10.23641/asha.22320814.

Item Response Theory Modeling of the Verb Naming Test.

Item response theory (IRT) is a modern psychometric framework with several advantageous properties as compared with classical test theory. IRT has been successfully used to model performance on anomia tests in individuals with aphasia; however, all efforts to date have focused on noun production accuracy. The purpose of this study is to evaluate whether the Verb Naming Test (VNT), a prominent test of action naming, can be successfully modeled under IRT and evaluate its reliability. We used responses on the VNT from 107 individuals with chronic aphasia from AphasiaBank. Unidimensionality and local independence, two assumptions prerequisite to IRT modeling, were evaluated using factor analysis and Yen's Q 3 statistic (Yen, 1984), respectively. The assumption of equal discrimination among test items was evaluated statistically via nested model comparisons and practically by using correlations of resulting IRT-derived scores. Finally, internal consistency, marginal and empirical reliability, and conditional reliability were evaluated. The VNT was found to be sufficiently unidimensional with the majority of item pairs demonstrating adequate local independence. An IRT model in which item discriminations are constrained to be equal demonstrated fit equivalent to a model in which unique discrimination parameters were estimated for each item. All forms of reliability were strong across the majority of IRT ability estimates. Modeling the VNT using IRT is feasible, yielding ability estimates that are both informative and reliable. Future efforts are needed to quantify the validity of the VNT under IRT and determine the extent to which it measures the same construct as other anomia tests. https://doi.org/10.23641/asha.22329235.

Traceability and comparability through crosswalks with the NeuroMET Memory Metric

Accurate assessment of memory ability for persons on the continuum of Alzheimer’s disease (AD) is vital for early diagnosis, monitoring of disease progression and evaluation of new therapies. However, currently available neuropsychological tests suffer from a lack of standardization and metrological quality assurance. Improved metrics of memory can be created by carefully combining selected items from legacy short-term memory tests, whilst at the same time retaining validity, and reducing patient burden. In psychometrics, this is known as “crosswalks” to link items empirically. The aim of this paper is to link items from different types of memory tests. Memory test data were collected from the European EMPIR NeuroMET and the SmartAge studies recruited at Charité Hospital (Healthy controls n = 92; Subjective cognitive decline n = 160; Mild cognitive impairment n = 50; and AD n = 58; age range 55–87). A bank of items (n = 57) was developed based on legacy short-term memory items (i.e., Corsi Block Test, Digit Span Test, Rey’s Auditory Verbal Learning Test, Word Learning Lists from the CERAD test battery and Mini Mental State Examination; MMSE). The NeuroMET Memory Metric (NMM) is a composite metric that comprises 57 dichotomous items (right/wrong). We previously reported on a preliminary item bank to assess memory based on immediate recall, and have now demonstrated direct comparability of measurements generated from the different legacy tests. We created crosswalks between the NMM and the legacy tests and between the NMM and the full MMSE using Rasch analysis (RUMM2030) and produced two conversion tables. Measurement uncertainties for estimates of person memory ability with the NMM across the full span were smaller than all individual legacy tests, which demonstrates the added value of the NMM. Comparisons with one (MMSE) of the legacy tests showed however higher measurement uncertainties of the NMM for people with a very low memory ability (raw score ≤ 19). The conversion tables developed through crosswalks in this paper provide clinicians and researchers with a practical tool to: (i) compensate for ordinality in raw scores, (ii) ensure traceability to make reliable and valid comparisons when measuring person ability, and (iii) enable comparability between test results from different legacy tests.

Heterosis and Combining Ability Estimate on Yield and Yield-Related Traits in a Half Diallel Crosses of Kenaf (Hibiscus Cannabinus L.) in Malaysia

ABSTRACT Understanding heterosis and combining ability among distinct kenaf (Hibiscus cannabinus L.) genetic resources is crucial for developing hybrid kenaf. An investigation was conducted on 36 F1 combinations produced from nine parental genotypes of kenaf in a diallelic scheme using Griffing diallel analysis technique 2, model I. Highly significant F-test values revealed the presence of variability for all the 15 quantitative traits for general combining ability (GCA) and specific combining ability (SCA) except days to 1st flowering. The magnitude of GCA variance was considerably higher than that of SCA variance for plant height, stem middle diameter, stem top diameter, days to flowering, number of pods, number of seeds and 1000 seeds weight, showing the predominates of additive gene for these traits. Narrow-sense heritability of 50.93% in the combined environments showed that seed number was the most heritable trait, whereas days to 1st flowering and 1000 seed weight had moderate heritability. Parents P1, P3 and P4 had the most dominant alleles for most traits studied. Considering SCA and heterosis values, the hybrids H3, H4, H9, H11, H23, H29 and H35 had high heterotic for fiber and seed yield.

Faster ≠ Smarter: Children with Higher Levels of Ability Take Longer to Give Incorrect Answers, Especially When the Task Matches Their Ability

The stereotype that children who are more able solve tasks quicker than their less capable peers exists both in and outside education. The F > C phenomenon and the distance-difficulty hypothesis offer alternative explanations of the time needed to complete a task; the former by the response correctness and the latter by the relative difference between the difficulty of the task and the ability of the examinee. To test these alternative explanations, we extracted IRT-based ability estimates and task difficulties from a sample of 514 children, 53% girls, M(age) = 10.3 years; who answered 29 Piagetian balance beam tasks. We used the answer correctness and task difficulty as predictors in multilevel regression models when controlling for children's ability levels. Our results challenge the 'faster equals smarter' stereotype. We show that ability levels predict the time needed to solve a task when the task is solved incorrectly, though only with moderately and highly difficult items. Moreover, children with higher ability levels take longer to answer items incorrectly, and tasks equal to children's ability levels take more time than very easy or difficult tasks. We conclude that the relationship between ability, task difficulty, and answer correctness is complex, and warn education professionals against basing their professional judgment on students' quickness.

Effectiveness of Collaboration in VET: Measuring Skills for Solving Complex Vocational Problems With a Multidimensional Authentic Technology-Based Assessment

Context:Collaboration and digitization in work and production process have been of scientific interest in the research field of vocational education and training for decades. So far, there is a lack of empirical evidence on the extent to which the performance of collaborative problem-solving can outperform individual problem-solving. An appropriate instrument for measuring collaborative performance appropriately has been lacking to this point: It is challenging to (1) collect data on interaction in collaboration in a standardized way and (2) to assign the individual performances to the group performance. In a web-based office simulation, this study examined the two-dimensional construct of collaborative problem-solving ability, which consists of cognitive and social components, and explored the effectiveness of collaboration.&#x0D; Methods:The test settings are systematically varied between individual and collaborative problem-solving in a domain-typical problem scenario in the economic domain. A theory-driven two-dimensional authentic instrument with a complex commercial problem in a web-based office simulation was applied to measure the performance in these two test settings. Multi-Group Confirmatory Factor Analysis was conducted to test for measurement invariance across test settings, the two-dimensional RASCH-Model incorporating between-item multidimensionality with correlated dimensions was used for ability estimation. ANOVA test was conducted to determine if there is a statistically significant difference with respect to the ability between the individual and collaborative test settings.&#x0D; Findings:The two-dimensional construct of collaborative problem-solving ability with correlated dimensions showed better fit than the unidimensional construct. The scalar measurement invariance was established after excluding three items. ANOVA tests confirmed that the collaborative setting enhances the problem-solving ability of learners significantly in both the cognitive component and social component, and the ability in cognitive component was more fostered.&#x0D; Conclusion:The findings suggested the validation of this multidimensional authentic instrument to measure the performance in a collaborative work environment in economic domains. The results showed the effectiveness of collaboration with a computer-based agent. In the practice of vocational training and education, teachers can use this instrument for the evaluation of the effectiveness of collaboration.

The Effects of Different Item Selection Methods on Test Information and Test Efficiency in Computer Adaptive Testing

The purpose of this study is to examine the effect of different item selection methods on test information function (TIF) and test efficiency in computer adaptive testing (CAT). TIF indicates the quantity of information the test has produced. Test efficiency resembles the amount of information from each item, and more efficient tests are produced from the smallest number of good-quality items. The study was conducted with simulated data, and the constants of the study are sample size, ability parameter distribution, item pool size, model of item response theory (IRT) and distribution of item parameters, ability estimation method, starting rule, item exposure control and stopping rule. The item selection methods, which are the independent variables of this study, are the interval information criterion, efficiency balanced information, matching -b value, Kullback-Leibler information, maximum fisher information, likelihood-weighted information, and random selection. In the comparison of these methods, the best performance in the aspect of TIF is provided by the maximum fisher information method. In terms of test efficiency, the performances of the methods were similar, except for the random selection method, which had the worst performance in terms of both TIF and test efficiency.

Enhancing Computerized Adaptive Testing with Batteries of Unidimensional Tests.

The article presents a new computerized adaptive testing (CAT) procedure for use with batteries of unidimensional tests. At each step of testing, the estimate of a certain ability is updated on the basis of the response to the latest administered item and the current estimates of all other abilities measured by the battery. The information deriving from these abilities is incorporated into an empirical prior that is updated each time that new estimates of the abilities are computed. In two simulation studies, the performance of the proposed procedure is compared with that of a standard procedure for CAT with batteries of unidimensional tests. The proposed procedure yields more accurate ability estimates in fixed-length CATs, and a reduction of test length in variable-length CATs. These gains in accuracy and efficiency increase with the correlation between the abilities measured by the batteries.

Исследование циклической трещиностойкости стали литых несущих деталей грузовых вагонов

Purpose: Carrying out complex experimental studies of cyclic crack resistance of molten steel which is used for load-bearing parts of freight wagon running systems with kinetic diagram building for fatigue failure. Methods: Method of mechanical testing of molten steel samples under cyclic loading conditions was applied, the method makes it possible to obtain quantitative estimates of stuff ability to resist fatigue failure on the stage of fatigue crack development (testing on cyclic crack resistance). To study the surface of fatigue failure, relief micrographic analysis was used. To study molten steel elemental composition and the mechanisms of fatigue crack development, X-ray micro-spectral analysis was used on fatigue failure various stages. Results: The results of the research of cyclic crack resistance of 20 GL molten steel, which is used for load-bearing parts of freight cars, are presented. Fatigue failure kinetic diagram has been built, detailed micrographic analysis of fatigue failure surface has been carried out and elemental composition of non-metallic inclusions has been studied. Practical significance: Based on the research results, it is possible to assess the performance of 20 GL steel with cracks and to predict survivability. The results obtained make it possible to improve the methods of resource projection of molten bearing parts for freight wagon running systems in order to increase their operational reliability. The research results are used by enterprises - manufacturers of molten parts to control technology stability and to improve product quality.

The Impact of Item Model Parameter Variations on Person Parameter Estimation in Computerized Adaptive Testing With Automatically Generated Items.

Sibling items developed through automatic item generation share similar but not identical psychometric properties. However, considering sibling item variations may bring huge computation difficulties and little improvement on scoring. Assuming identical characteristics among siblings, this study explores the impact of item model parameter variations (i.e., within-family variation between siblings) on person parameter estimation in linear tests and Computerized Adaptive Testing (CAT). Specifically, we explore (1) what if small/medium/large within-family variance is ignored, (2) if the effect of larger within-model variance can be compensated by greater test length, (3) if the item model pool properties affect the impact of within-family variance on scoring, and (4) if the issues in (1) and (2) are different in linear vs. adaptive testing. Related sibling model is used for data generation and identical sibling model is assumed for scoring. Manipulated factors include test length, the size of within-model variation, and item model pool characteristics. Results show that as within-family variance increases, the standard error of scores remains at similar levels. For correlations between true and estimated score and RMSE, the effect of the larger within-model variance was compensated by test length. For bias, scores are biased towards the center, and bias was not compensated by test length. Despite the within-family variation is random in current simulations, to yield less biased ability estimates, the item model pool should provide balanced opportunities such that "fake-easy" and "fake-difficult" item instances cancel their effects. The results of CAT are similar to that of linear tests, except for higher efficiency.

Combining ability estimates for quality and non-quality protein maize inbred lines for grain yield, agronomic, and quality traits

IntroductionBiofortified maize varieties could contribute to the fight against hunger and malnutrition of the increasing human population and help meet the high demand of maize for human consumption, industrial use and feed for animal and poultry. The understanding of the genetic mechanisms conditioning the inheritance of grain yield and other agronomic and quality traits is essential in the development of superior maize genotypes. The main objective of this study was to determine the combining ability for grain yield and other agronomic traits of QPM and non-QPM inbred lines crossed with two QPM and two non-QPM testers.Materials and methodsA total of 130 hybrids were obtained by crossing 10 non-QPM and 23 QPM lines with four elite testers (two QPM and two non-QPM). The 130 single cross hybrids were evaluated at 13 sites in 2018 and 2019.Results and discussionThe results showed significant general combining ability (GCA) for lines and testers as well as significant specific combining ability (SCA) for hybrids for most of the measured traits. Non-additive gene action controlled the inheritance of grain yield while agronomic and quality traits were controlled by additive gene action. QPM lines 11, 14 and 28 and non-QPM tester CML444 showed desirable GCA effects for grain yield, indicating that these lines in combination with tester CML444 should be considered when targeting development of superior maize genotypes with QPM traits.ConclusionsBased on the SCA values, crosses 120, 108, 105, 99, 85, and 41 were identified as the best hybrids across the locations. It is recommended that maize breeding programs targeting the development of high yielding QPM hybrids should exploit QPM lines with high GCA values for heterosis to be realized. In addition, the identified superior hybrids may be further evaluated and consequently promoted for commercial release which could increase incomes of farmers and help to alleviate poverty, hunger and malnutrition in southern Africa and sub-Saharan Africa at large.