Machine learning for multi-criteria inventory classification applied to intermittent demand

Multi-criteria inventory classification groups inventory items into classes, each of which is managed by a specific re-order policy according to its priority. However, the tasks of inventory classification and control are not carried out jointly if the classification criteria and the classification approach are not robustly established from an inventory-cost perspective. Exhaustive simulations at the single item level of the inventory system would directly solve this issue by searching for the best re-order policy per item, thus achieving the subsequent optimal classification without resorting to any multi-criteria classification method. However, this would be very time-consuming in real settings, where a large number of items need to be managed simultaneously. In this article, a reduction in simulation effort is achieved by extracting from the population of items a sample on which to perform an exhaustive search of best re-order policies per item; the lowest cost classification of in-sample items is, therefore, achieved. Then, in line with the increasing need for ICT tools in the production management of Industry 4.0 systems, supervised classifiers from the machine learning research field (i.e. support vector machines with a Gaussian kernel and deep neural networks) are trained on these in-sample items to learn to classify the out-of-sample items solely based on the values they show on the features (i.e. classification criteria). The inventory system adopted here is suitable for intermittent demands, but it may also suit non-intermittent demands, thus providing great flexibility. The experimental analysis of two large datasets showed an excellent accuracy, which suggests that machine learning classifiers could be implemented in advanced inventory classification systems

Recent advances in the theory and practice of logical analysis of data

Logical Analysis of Data (LAD) is a data analysis methodology introduced by Peter L. Hammer in 1986. LAD distinguishes itself from other classification and machine learning methods by the fact that it analyzes a significant subset of combinations of variables to describe the positive or negative nature of an observation and uses combinatorial techniques to extract models defined in terms of patterns. In recent years, the methodology has tremendously advanced through numerous theoretical developments and practical applications. In the present paper, we review the methodology and its recent advances, describe novel applications in engineering, finance, health care, and algorithmic techniques for some stochastic optimization problems, and provide a comparative description of LAD with well-known classification methods

Validity of the overclaiming technique as a method to account for response bias in self-assessment questions : analysis on the basis of the PISA 2012 data

The presented work is devoted to study the validity of overclaiming technique (OCT) as a measure of response (positivity) bias. Three main aims of the analyses performed were: a) assess methods' utility to enhance predictive validity of self-report by accounting for response biases, b) investigate proposed mechanisms of overclaiming, c) expand nomological network of the method by presenting a wide set of both individual-level and cluster-level (school) correlates. The obtained results pointed that OCT can be used in order to account for response biases in self-report data. Important differences regarding use and interpretation of the different OCT scoring systems were found and commented. Two systems, one based of signal detection theory (SDT), other on item response theory model (IRT), were proposed as viable scorings of OCT. Choice between them is not trivial as it influences results' interpretation and model specification. Three possible mechanisms of overclaiming were tested: a) motivated response bias (self-favouring bias, socially desirable responding), b) memory bias (overgeneralised knowledge or faulty memory control) and c) response styles and careless responding. The results pointed that all three mechanisms are probable and that overclaiming is most probably a heterogenous phenomenon of multiple causes. However, the analyses pointed out that one of the memory bias hypotheses, the overgeneralised knowledge account, does not hold and that there is much more evidence for the competitive metacognitive account. It is to said that overclaiming is at least partially attributable to insufficient monitoring of one's knowledge. Evidence for a relation between careless responding and overclaiming was also obtained, indicating that at least some of the overclaimed responses can be attributed due to inattentive responding. Obtained results on the relations between response styles and overclaiming were complicated; they warrant further studies as the results here probably greatly depend on the technical details of analysis, e.g. response style definition and coding adopted. The analysed cluster-level covariates demonstrated that only very limited portion of OCT variance can be ascribed to the school-level of analysis. Gender, socio-economic status and locus of control proved to be significantly related to overclaiming among the individual-level correlates assessed. Boys yielded higher overclaiming bias than girls and students of external locus of control were more biased in their self-reports in comparison to students of internal locus of control. The work comprises also analysis of the PISA's OCT latent structure. The results evidenced bifactor structure of the scale, with the general factor interpreted as math ability while the two specific factors were given a tentative explanation concentrated around item difficulty (one specific factor emerged for easy items, one for hard items). These findings point to a multi-dimensional character of OCT and a large role played by domain ability in OCT responding. Moreover, latent class analysis (LCA) performed identified an "overclaiming" group among the participants which was characterised by high overclaiming and unwarrantedly high self-report profile regarding math-related abilities and social life. However, this group counted only around 9% of the total sample. Implications of these findings are commented in the work, along with theoretical integration and ideas for future studies with the use of OCT

Demographic and Psychiatric Correlates of Performance Validity Profiles of Individuals Assessed Subsequent to Motor Vehicle Accidents

The current study explored the effects of cultural, demographic and psychiatric variables on Performance Validity Test (PVT) base rates of failure (BRFAIL) in 325 examinees with traumatic brain injury (TBI) following motor vehicle accidents. PVTs are widely used measures of credibility in neuropsychological assessment. Gaps in the PVT literature regarding the effects of various demographic, cultural, and psychiatric factors limit the generalizability of PVTs. Higher false-positive rates in minority groups may lead to the inaccurate characterization of members as noncredible, resulting in the denial of treatment and compensation following injuries. To address this gap in the literature, the first objective of the study explored the relationship between BRFAIL, and limited English proficiency, time spent in Canada, education, age, gender, and injury severity. Results indicated that examinees with limited English proficiency had higher BRFAIL on PVTs with low verbal mediation (i.e., tests that did not have verbal components beyond the instructions) compared to Anglophone Canadians. Examinees who had language interpreters had higher BRFAIL on PVTs with both high and low verbal mediation compared to examinees assessed in English. Examinees who immigrated to Canada had higher BRFAIL on both high and low verbal mediation PVTs compared to Canadian-born examinees. Examinees aged 40 to 49 and those with less than high school education had higher BRFAIL for low verbal mediation PVTs than other groups. There were no differences for gender or TBI severity on BRFAIL. These results may be explained by several cultural factors, including cultural concepts of distress and differences in health literacy, which may contribute to PVT BRFAIL. As such, neuropsychologists should consider the contribution of these cultural factors when interpreting PVT results of examinees who have immigrated to Canada. Another important gap in the literature is in regards the relationship between PVTs and dissociative symptoms (i.e., disrupted consciousness, affect, and memory). Findings on the effects of psychiatric factors (e.g., posttraumatic, depressive, and anxious symptoms) on PVT BRFAIL are mixed but generally indicate that PVTs are robust to psychiatric disorders except psychosis. However, disruptions in consciousness, memory, and affect due to dissociative pathology might be expected to interfere with test performance. The second objective of this study explored the relationship between BRFAIL and dissociative, posttraumatic, anxious, and depressive symptoms. Results indicated elevated rates of PVT BRFAIL for examinees with higher levels of self-reported posttraumatic, depressive, and anxious symptoms. Results also indicated that those with high self-reported dissociative symptoms had higher BRFAIL for verbally mediated PVTs. The findings suggest that dissociative symptoms may interfere with verbally mediated PVTs, and highlight the need for further research into the effects of dissociative pathology on neuropsychological and PVT performance. The current study demonstrated that previously unexplored cultural, demographic, and psychiatric factors are related to PVT performance, and may affect the interpretation of PVTs. Implications, limitations, and avenues for future research are discussed

Cognitive social and affective neuroscience of patients with spinal cord injury

A successful human-environment interaction requires a continuous integration of information concerning body parts, object features and affective dynamics. Multiple neuropsychological studies show that tools can be integrated into the representation of one's own body. In particular, a tool that participates in the conscious movement of the person is added to the dynamic representation the body – often called “Body schema” – and may even affect social interaction. In light of this the wheelchair is treated as an extension of the disabled body, essentially replacing limbs that don't function properly, but it can also be a symbol of frailty and weakness. In a series of experiments, I studied plastic changes of action, tool and body representation in individuals with spinal cord injury (SCI). Due to their peripheral loss of sensorimotor functions, in the absence of brain lesions and spared higher order cognitive functions, these patients represent an excellent model to study this topic in a multi-faceted way, investigating both fundamental mechanisms and possible therapeutic interventions. In a series of experiments, I developed new behavioral methods to measure the phenomenological aspects of tool embodiment (Chapter 3), to study its functional and neural correlates (Chapter 4) and to assess the possible computational model underpinning these phenomena (Chapter 5). These tasks have been used to describe changes in tool, action and body representation following the injury (Chapter 3 and 4), but also social interactions (Chapter 7), with the aim of giving a complete portrait of change following such damage. I found that changes in the function (wheelchair use) and the structure (body brain disconnection) of the physical body, plastically modulate tool, action and body representation. Social context and social interaction are also shaped by the new configuration of bodily representations. Such a high degree of plasticity suggests that our sense of body is not given at once, but rather it is constantly constructed and adapted through experience

Uncovering the root cause of ethnic difference in ability testing:differential test functioning, test familiarity and trait optimism as explanations of ethnic group differences

The present research represents a coherent approach to understanding the root causes of ethnic group differences in ability test performance. Two studies were conducted, each of which was designed to address a key knowledge gap in the ethnic bias literature. In Study 1, both the LR Method of Differential Item Functioning (DIF) detection and Mixture Latent Variable Modelling were used to investigate the degree to which Differential Test Functioning (DTF) could explain ethnic group test performance differences in a large, previously unpublished dataset. Though mean test score differences were observed between a number of ethnic groups, neither technique was able to identify ethnic DTF. This calls into question the practical application of DTF to understanding these group differences. Study 2 investigated whether a number of non-cognitive factors might explain ethnic group test performance differences on a variety of ability tests. Two factors – test familiarity and trait optimism – were able to explain a large proportion of ethnic group test score differences. Furthermore, test familiarity was found to mediate the relationship between socio-economic factors – particularly participant educational level and familial social status – and test performance, suggesting that test familiarity develops over time through the mechanism of exposure to ability testing in other contexts. These findings represent a substantial contribution to the field’s understanding of two key issues surrounding ethnic test performance differences. The author calls for a new line of research into these performance facilitating and debilitating factors, before recommendations are offered for practitioners to ensure fairer deployment of ability testing in high-stakes selection processes

Metamemory in multiple sclerosis

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The concept of metamemory proposes that supplementary to typically measured memory abilities, memory monitoring and control processes are used to optimise learning. Accurate memory monitoring appears to be underpinned by a range of cognitive, and possibly affective, contributions. In populations with these deficits, metamemory has been shown to be impaired. In Multiple Sclerosis (MS), only a limited metamemory literature exists, surprising given that MS is a leading cause of disability among people of working age, and cognitive and mood disorder is common. Using structural equation modelling, this study of 100 people with MS explored factors contributing to performance on episodic Judgment of Learning, Retrospective Confidence and Feeling of Knowing. Given its negative influence on cognitive domains in MS, the impact of information processing deficits on metamemory was also investigated. Finally, memory self-report, a frequently used clinical indicator of memory functioning, was assessed. Findings suggest that memory complaint is associated with mood, and is unrelated to tested memory. Second, Retrospective Confidence Judgments were predictive of memory performance, even in the presence of memory impairment. Third, an unusual finding of maintained underconfidence at delay was observed in the Judgment of Learning task. Finally, Feeling of Knowing judgments related to executive, but not to memory ability. A novel finding in respect of this judgment was of processing speed relating negatively to accuracy, in the context of executive dysfunction. This suggests that some top-down direction of processing resources may be a factor in supporting accuracy, rather than the speed at which information is processed. Of all the task-based judgments, accuracy in this judgment was the only one with a reliable association with mood. Faster processing speed, executive dysfunction and least depression symptomatology related to low accuracy, perhaps typifying a profile of disinhibition seen in MS, characterised by poorly constrained processing and apparently elevated mood

Intuition for the intuitive : On the interplay between lay conceptions of intuition and the influence of intuition appeals in persuasion

Tese apresentada para cumprimento dos requisitos necessários à obtenção do grau de Doutor em Psicologia na área de especialização de Psicologia Social apresentada no ISPA - Instituto Universitário no ano de 2021