Master of Science

Undependable systems are unable to accomplish the mission for which they were designed and cause tremendous loss [Airwar-Vietnam, 1978]. In most instances, timely maintenance is a vital necessity for a system to be kept in or returned to its operating condition, and to be able to successfully complete a specific mission. In a scarcer-resource but higher-competition environment, it is essential that system dependability be considered as a major system parameter and be evaluated during the early phases of the system design process. Given a specific system mission profile, whether or not the mission can be successfully completed is based not only on such measures as performance, reliability, maintainability, and/or availability. There is a need for system designers and engineers to meeasure system dependability, as well. System dependability is a measure of effectiveness which allows for the consideration of maintenance in the life cycle as long as it does not inhibit the system from fulfilling its mission. It is the aim of this project to develop a methodology for the analysis and evaluation of system effectiveness through the utilization of the system dependability measure. The concept and the mathematical model of system dependability is discussed. Effectiveness factors and relationships are described, a measure of system dependability has been defined, and a computer -based tool was developed to enable the accomplishment of trade-off analyses and the evaluation of various system configurations in terms of dependability. Maintenance requirements are addressed through the introduction of various combinations of failures, and failure distributions include the consideration of the exponential, Weibull, and log-normal cases. Application of the dependability model is illustrated through a case study involving an aircraft radar trated through a case study involving an aircraft radar is illustrated through a case study involving an aircraft radar subsystem as an example. / Master of Science

Job satisfaction has, and continues to be an important construct of interest to researchers and practitioners alike. However, conflicting operational definitions and inconsistent measurement systems have reduced the efficacy of the construct in predicting important job-related outcomes for organizations and their employees. The Facet Satisfaction Scale (FSS) was designed to overcome these deficiencies by creating a facet-based measure that assesses job satisfaction in accordance with recent definitions of the construct. Reliability and validity analyses were conducted on both the complete and shortened version of the scale. The FSS exhibited evidence of reliability (ranging from .52 to .93 for the shortened FSS, and .53 to .96 for the complete FSS). Evidence of scale validity was also obtained through the use of construct, content, and criterion-related validity measures. Implications of the study on future research on job satisfaction are discussed.

Introduction and objectives: COVID-19 has generated negative consequences for people's mental health. This is the case of Peru, one of the Latin American countries most affected by the pandemic. In this sense, the objective of the study was to translate and validate the Coronavirus Anxiety Scale (CAS) into Spanish. Material and method: The participants were 704 university students of health sciences (Mage = 23.39 years, SD = 3.45) who were administered the CAS in Spanish, the Mental Health Inventory-5 and the Patient Health Questionnaire-2 item. The CAS was translated into Spanish using the forward and backward method. Reliability and evidence of validity based on internal structure and relationship with other variables were examined. Results: The factor analysis confirmed the one-dimensional factor structure of the CAS (χ2 = 7.62, df = 5, p = .18, χ2 / gl = 1.52, CFI = .99, RMSEA = .03 [90% CI. 00,. 06]; SRMR = .02, WRMR = .52); In addition, the factor loadings were large and significant (from. 68 to. 87). The five CAS items showed acceptable corrected total test item correlations (from. 64 to. 74). Reliability due to internal consistency was good (ω = .89; αordinal = .89). The validity evidence based on the relationship with other CAS variables was supported by the positive correlation with depression (r = .52, p < .01) and negative with subjective well-being (r = -.50, p < .01). Furthermore, depression mediates the relationship between COVID-19 anxiety and subjective well-being (bootstrap value = -. 24, 95% CI = -. 28, -. 20). Conclusion: The Spanish version of the CAS has evidence of validity and reliability to measure anxiety by COVID-19 in a sample of Peruvian university students.

This dissertation motivates and defends what I call non-inferential epistemic circularity. Traditionally epistemic circularity is understood to be a property of arguments, where justification to believe these arguments’ premises depends upon the truth of their conclusions. I argue that epistemically circular arguments face a dilemma. If the conditions for non-inferential justification to believe their premises are too weak, these arguments are either indiscriminate or permit one to bootstrap trivially to higher-order justification. If to avoid these problems the conditions for non-inferential justification are strengthened on the basis of evidence, then epistemically circular arguments beg the question because they collapse into logical circularity. To address these problems I argue that an account of non-inferential justification should be developed that limits the role of evidential grounds and finds room instead for non-evidential sources of justification. I conclude that epistemic circularity is constitutive of non-inferential justification because it is a property of the intentional acts in virtue of which this justification is earned.

The Institute for Test Research and Test Development (ITT) has provided complimentary Vocabulary Size Tests (VST) in 15 languages to language learners and their teachers, measuring their own or their learners’ receptive and productive vocabulary sizes. This report examines in detail and on a large empirical basis the validity and reliability of these tests.

Introduction: The aim of the present study was the cross-cultural adaptation and validation of the Vocal Fatigue Index (VFI) in Persian. Methods: The English version of the VFI was translated to Persian using the guidelines of International Quality of Life Assessment. Eighty participants with voice disorders and 50 healthy controls without any voice disorders completed the Persian version of the VFI. The 80 participants with voice disorders completed the VFI a second time a week from the initial completion to evaluate test-retest reliability. Results: The VFI measure demonstrated a strong internal consistency. Cronbach alpha coefficient was 0.95 for tiredness and avoidance of voice use, 0.86 for physical discomfort and 0.83 for improvement or lack thereof of symptoms with voice rest. VFI also showed a high test-retest reliability (r = 0.75–0.89). Conclusions: The Persian version of the VFI is considered to be a valid and reliable questionnaire for identifying individuals with probable vocal fatigue. The VFI can be utilized in clinics across Iran in the assessment and treatment of individuals with vocal fatigue.

Software testing is a widely used quality assurance activity and often starts from the early development stages. However, starting early in the development process raises difficulties and challenges practitioners must deal with; most typically, hardware is not available in the required quantities, and there is the risk of damaging the hardware while testing. Emulating the physical hardware into virtual versions is a popular approach to overcome the mentioned obstacles. This master thesis, carried out at Westermo AB, investigates the differences between the physical and virtual hardware used for embedded system software testing and the possible benefits of combining both hardware versions in a hybrid system. Investigating differences between the hardware options helps identify which type of tests are more suitable in physical versus virtual hardware. The selected method for this thesis is a case study, starting with a pre-study phase investigating how other industries tackle the difficulties and challenges mentioned. Further, data were collected from two sources, historical test reports, and a questionnaire. The historical test reports showed a timing difference between virtual and physical hardware. The reset process of physical hardware is often faster than virtual hardware, but the link-up/link-down time is slower in physical hardware. The questionnaire also confirmed the timing differences as a significant challenge often experienced by engineers. Another challenge highlighted by the questionnaire answers is that "false positives" are typically caused by virtual hardware, where issues do not always turn up due to the virtual nature of communication. Another difference proven from this thesis is that virtual hardware is more failure-prone during the early stages of testing than physical hardware. The hybrid system could be advantageous in various ways, such as quantitatively expanding the current test systems and increasing test coverage. Future work could contribute with a proof-of-concept implementation of the hybrid system to confirm the advantages and demonstrate the third option of a test system.

Objective: Mindfulness or the full attention state is a factor that contributes to the successful process of aging. This study aims to evaluate the evidence of validity, on the basis of the internal structure, convergent and discriminant validity, reliability and factorial invariance across gender, for the five items Mindful Attention Awareness Scale (MAAS-5) within a sample of older adults. Methods: The participants were 323 Peruvian older adults, consisting of 160 women and 163 men, whose average ages were 68.58 (S.D = 7.23) and 68.91 years (S.D = 7.12), respectively. In addition to the MAAS-5, the Satisfaction with Life Scale and the Patient Health Questionnaire-2 were administered. Results: The Confirmatory Factor Analysis indicates that the one-factor structure of the MAAS-5 presents adequate fit for the total sample (χ2 = 11.24, df = 5, χ2/df = 2.25, CFI =.99, RMSEA =.06 [90%CI:.01,.11]; and SRMR =.025), as well as for the sub-samples of men and women. This one-factor solution presents adequate internal consistency (ω = 80 [95%CI:.76 -.82]) and it is invariant across gender. Regarding convergent validity, high scores in the MAAS are associated with a greater satisfaction with life (r =.88, p<.01 [95%CI:.85,.95]) and less depression (r = −.56, p<.01 [95%CI: −.48, −.77]) in older adults. Conclusions: The preliminary results back the use of the MAAS-5 as a self-report measure of mindfulness that has an adequate unifactorial structure that is reliable and invariant across gender for measuring the full attention state in elderly Peruvians.

The intent of this thesis is to investigate, develop, and apply techniques to determine the reliability and maintainability of populations of items. These techniques are to be used in determining the total life-time operating costs of the populations so that those items with the lowest life-time costs can be bought. To do this, the author has explored current techniques for determining compliance to some minimum required Mean Time Between Failure (MTBF) in what is referred to as a Phase I testing. After the requirements of Phase I testing have been met, testing may be continued at the option of the contractor and confidence limits constructed about the Bid MTBF to determine compliance to it. Methods by which incentives or penalties may be rewarded or assessed to contractor as a result of the Phase II testing are included. The author next investigated techniques which can be used to determine the maintainability parameters and the accuracy of these parameters. Finally, since the reliability techniques explored were all based on the exponential distribution, techniques were included to prove if the failure rate was exponential. If not, discussions were incorporated on how to handle this situation. (85 pages)