Browsing by Subject "reliability"

Now showing 1 - 8 of 8
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    Correlates of Annual Testing for Sexually Transmitted Infections (STIs) in an Online Sample of Men Who Have Sex with Men (MSM): Study Sample Validity, Measure Reliability, and Behavioral Typologies
    (2013-07) Grey, Jeremy
    Objective: Testing for STIs has been prioritized as part of a comprehensive HIV/AIDS prevention plan. Internet-based studies of STI testing among men who have sex with men (MSM) are efficient methods of recruiting non-clinic samples from diverse geographic areas. However, online survey methods raise unique concerns regarding threats to the validity of study samples and unknown measurement properties. Thus, this dissertation had two aims. The first was to examine methods related to online survey research by evaluating a protocol to detect invalid survey entries and determining the test-retest reliability of online measures of sexual behavior and STI testing. The second aim was to use the validated sample and reliable measures to examine correlates of STI testing in the year prior to the survey. Methods: In Manuscript 1, survey submissions were classified as valid and invalid according to a de-duplication and cross-validation protocol. Logistic regression models were used to determine associations between invalidity and key demographic and behavioral variables. In Manuscript 2, test-retest reliability over one week was evaluated using intraclass correlation coefficients (ICCs) and kappa statistics for measures of sexual behavior, HIV status, HIV testing, and STI diagnoses. Finally, in Manuscript 3, the valid sample from Manuscript 1 and measures that were evaluated in Manuscript 2 were used to examine the clustering and correlates of STI testing behaviors. Results: In Manuscript 1, three components of the protocol for detecting invalid submissions were responsible for identifying the most invalid survey submissions: duplicate IP address, changed eligibility responses, and duplicate payment name. A total of 146 (11.6%) of the submissions were identified as invalid. Invalid submissions had lower odds of reporting HIV testing in the past year. Hispanic/Latino identity, age, and HIV status were also significantly associated with invalidity. In Manuscript 2, counts of sexual partners (three months), HIV status, HIV testing, and STI diagnoses were found to have substantial (0.61-0.80) to almost perfect (0.81-1.00) seven-day test-retest reliabilities, according to commonly used cutpoints. Partner-specific data, however, were only fairly or moderately reliable (0.21-0.60). Finally, in Manuscript 3, a latent class analysis indicated five STI testing classes: no STIs, all STIs, bacterial STIs and hepatitis, bacterial STIs only, and hepatitis only. The largest class was no STIs, indicating that 45.8% of the validated sample had not been tested for STIs in the past year. Predictors of being in a testing class versus no STI testing included age, education, outness about having sex with men, HIV status, and having a sexual partner in the last three months. Conclusions: This dissertation served two primary aims. The first was to evaluate sample validity and measure reliability in an online study of MSM. The second was to apply the information from those analyses to examine the presence and correlates of a latent variable of STI testing. Across all three manuscripts, online survey research appears to be a viable method of studying STI testing in Internet-based samples of MSM.
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    The Effect of Incorporating Active Learning In Calibration Exercises On Intra and Interrater Reliability Among Dental Hygiene Faculty
    (2019-09) Hotzler, Bridget
    ABSTRACT Purpose/Objective: The purpose of this study was to investigate if incorporating active learning into calibration exercises increased the level of intra- and interrater reliability among dental hygiene faculty. Methods: The study used a two-group randomized experimental design with a convenience sample consisting of ten dental hygiene faculty members from the division of dental hygiene at the University of Minnesota (n=10). Baseline training in motivational interviewing (MI) was provided to all faculty at a day-long continuing education course. One month later, all faculty viewed three videos of students performing MI during an OSCE and graded their performance using a standardized grading rubric. The treatment group then engaged in the identical motivational interviewing OSCE required of the students. One month later, both study groups viewed the same three videos and graded the students’ MI performance using the identical standardized grading rubric. (See Appendix C). Results: The overall intra-rater reliability was calculated using Cohen’s Kappa statistic, pre-and post-intervention for both the control and treatment groups. Results revealed moderate to weak intra-rater reliability for both groups (.494). Fleiss’ kappa statistic was used to assess interrater reliability. The treatment group achieved higher levels of agreement verses the control group on six of the ten questions. Only one question (See Figure 1: R06) had perfect or near perfect agreement in both study groups. Conclusion: There was no statistically significant difference found in intra- and interrater reliability scores between the control and treatment groups following an active learning intervention. Even though statistical significance was not achieved, individual faculty data suggests active learning did have an effect on the faculty in the treatment group. Post intervention, faculty in the treatment group had greater variations in scores indicating the experience had challenged their frame of knowledge and may have become more empathetic to the challenges of motivational interviewing having conducted an MI session themselves.
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    Electromigration-Induced Interconnect Aging and its Repercussions on the Performance of Nanometer-Scale VLSI Circuits
    (2016-06) Mishra, Vivek
    Modern electronic machines are powered by the integrated-circuit (IC), a semiconductor device consisting of compact electronic circuits on a silicon substrate. ICs can contain over a billion fundamental computing elements (transistors) that are connected by a network of metal wires called interconnects. Presently, interconnects constitute a primary bottleneck in achieving required IC performance. One of the major hurdles towards achieving good interconnect performance is electromigration (EM), a physical wear-out mechanism that occurs in metal wires carrying electrical current. EM is projected to limit the performance in future generations of ICs, especially for the wires carrying unidirectional (DC) currents, and is becoming a growing concern in on-chip interconnects across applications ranging from mobile computing to automotive domains. EM results in redistribution of metal atoms in interconnects that may result in the formation of either voids (empty spaces inside the wire) or extrusions (metal accumulation into the dielectric), and for modern copper-based interconnects, experimental works have observed that failure happens typically through the formation and growth of voids. For modern interconnects carrying large current densities, EM-induced voids can cause a resistance increase in the wire, rendering a wire EM-mortal. The resistance increase in these mortal interconnects can potentially result in circuit performance failure within the lifetime of a product. The classical methods for EM circuit analysis that are used in the industry to design EM-safe ICs do not capture the reality of EM physics in the realm of modern copper-based interconnects. IC designers use simple, deterministic, empirical EM models and there is a significant gap between such empirical models and the physics-based models that accurately capture the effect of EM in interconnects. The focus of this thesis is to attempt to reduce this gap by combining the two types of models efficiently, capturing the essence of physics-based models into the IC design, thereby enabling the design of EM-robust IC in future technologies. Unlike the classical EM analysis methods that rely on determining failure by extrapolating the EM characteristics of isolated single wires to IC operating conditions, the approach described in this thesis captures the circuit context and uses system failure rather than single-wire failure as the criterion for determining the lifetime of a circuit. The first part of the thesis proposes a statistical framework to evaluate the circuit performance degradation in on-chip wires through circuit level analysis. Typical on-chip power grids are inherently robust to EM due to redundancies in the interconnect network structure. In these grids, where interconnects typically carry unidirectional currents, the traditional approach to EM analysis is based on the weakest link model, whereby a single wire failure causes the grid to fail. It is shown here that the power grid can maintain supply integrity even under multiple elemental failures, and this can result in longer and more realistic lifetime predictions as compared with classical approaches. The next part of the thesis addresses signal interconnects that carry bidirectional (AC) currents as they transport logic signals within the digital system. For these wires, it is shown that EM is not only a catastrophic failure problem, but is also capable of causing parametric shifts in circuit performance over time. We perform HSPICE-based Monte Carlo simulations on a standard on-chip structure to quantify the impact of EM on circuit performance degradation. Although the damage due to EM degradation under bidirectional currents is reduced relative to the unidirectional current case due to partial EM recovery, it is demonstrated that, depending on the level of recovery, the circuit performance may degrade beyond acceptable limits and can be comparable to other transistor degradation mechanisms. The third part of the thesis addresses the issue of EM mortality in interconnects. A wire may be prevented from being mortal under EM if the maximum stress build-up, corresponding to the equilibrium between the current-induced forward stress and the back stress due to the gradient in atomic concentration along the wire, does not exceed the critical stress due to void nucleation. Alternatively, it may also not be mortal if the stress build-up does not exceed the critical stress over the lifetime of the circuit. A new efficient approach, based on multiple filters, is developed for determining the mortality of wires in a circuit. These filters greatly reduce circuit analysis time by predicting which wires can never be mortal over the circuit lifetime under its operating conditions so that detailed analysis must only be performed over a small subset of all interconnects. The final part of the thesis studies the effect of EM on via arrays, which redundantly connect the wires in multiple levels of metal in an IC. A stress analysis technique for via arrays is proposed, accounting for differential coefficients of thermal expansion in the materials that make up these structures. The combined impact of thermomechanical stress and redundancy on the via array is determined, and a new model for the impact on the failure of a larger interconnect network is developed. Using the new model, we analyze the EM-induced performance degradation in via arrays of an industrial power grid benchmark circuit.
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    In Search of The Psychosis Continuum In The Human Connectome
    (2020-09) Ma, Yizhou
    Psychosis is known to exist on a continuum in the population, ranging from infrequent, subclinical psychotic-like experiences to full-blown psychotic disorders. Resting-state functional connectivity studies report widespread dysconnectivity at various points along the psychosis continuum, yet a comprehensive mapping of psychosis in the human connectome remains elusive. This dissertation aims to build a resting-state functional connectivity model reproducible and generalizable across the psychosis continuum with a systematic approach to large community and clinical samples. Measurement properties of the human connectome derived with various methods were first compared to identify the human connectome with optimal test-retest reliability. The identified human connectome was then used to build a cross-validated model for psychotic-like experiences in a large community sample (N = 855). Lastly, this model was validated in a clinical sample with patients with psychosis and first-degree relatives. Findings suggest that independent component analysis with dimensionalities above 100 yielded human connectomics with optimal reliability. A model involving primarily connections in the frontoparietal, default, cingulo-opercular, and dorsal attention networks explained as much as 3.4% of variance in psychotic-like experiences in healthy adults. In the clinical sample, model score explained psychoticism and schizotypy across patients with psychosis, first-degree relatives, and healthy controls (partial correlation ranged from 0.19 to 0.51). Findings provide direct evidence for the psychosis continuum encoded in the human connectome. The quantifiable resting state functional connectivity model facilitates validation in additional samples and shows preliminary potential for clinical utility.
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    A Probabilistic Model for Failure of Polycrystaline Silicon MEMS Structures
    (2015-05) Zhu, Zhiren
    Reliable MEMS devices are expected to have a very low failure probability, and thus it is cost-prohibitive to determine design strength values merely based on extensive histogram testings. A theoretical understanding of probabilistic failure in the structure is critical for reliability analysis of MEMS devices. Prediction of failure statistics for MEMS structures are commonly based on the classical Weibull's model for material strength, which has been experimentally proven to be incapable of optimally fitting the failure probability distribution of MEMS structures. A generalized finite weakest-link model is developed to describe the strength statistics of polycrystalline silicon (poly-Si) MEMS structures. Different from the classical Weibull statistics based on extreme value statistics, the present model is applicable for poly-Si structures of all sizes. The overall failure probability of the structure is related to the failure probability of each material element along its sidewalls through a weakest-link statistical model. For each material element, the failure statistics is determined by both the random material strength and stress field induced by random sidewall geometry. The model is shown to agree well with measured strength histograms of poly-Si MEMS specimens of different sizes, and the calibrated mean strength of the material element is in accordance with theoretical strength of silicon. The strength statistics is further related to the effects of structure size on the mean structural strength, and an efficient method to determine the failure statistics of MEMS structures is proposed based on the present model.
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    The Role of the Market and Competition in M.B.A. Degree Program Rankings: The Reliability and Validity of Rankings of M.B.A. Programs
    (2016-06) Horner, Olena
    In light of increasing popularity of rankings of M.B.A. programs among prospective students, employers, and the general public, this dissertation research seeks to explore five ranking systems of full-time M.B.A. programs in the United States: U.S. News & World Report, Bloomberg Businessweek, The Financial Times, The Economist, and Forbes, from four different perspectives. First, the study assesses the quality of the M.B.A. rankings through the lens of the Berlin Principles on Ranking of Higher Education Institutions. Further, the study compares the resulting ranking of M.B.A. rankings, which is based on the objective quality assessment of these ranking systems, with students’ evaluation of the importance of various M.B.A. rankings for their decision to enroll as reported in the 2012 mba.com Prospective Students Survey (Graduate Management Admission Council, 2012b). The finding that only the top two rankings were the same brings into focus the necessity for a better alignment between the two groups. Second, by exploring first-order autocorrelation of the error terms for the four rankings of M.B.A. programs: U.S. News & World Report, Bloomberg Businessweek, The Financial Times, and Forbes, this study demonstrates that methodological changes made to these rankings between 2000 and 2013 have enhanced their reliability in terms of predictability, which suggests that ranking entities have made an effort to improve their methodologies. The results of the correlational analysis of the five M.B.A. ranking systems in the United States across 14 years strongly support the hypothesis about the stability of ranking scores. The examination of convergent and discriminant validity of the Bloomberg Businessweek M.B.A. rankings using multitrait-multioccasion confirmatory factor analysis provided evidence for the validity of measures that are used in the rankings of M.B.A. programs to determine the hypothetical construct of quality of an M.B.A. program. Third, by examining the anchoring effect of rankings and reputation in higher education, this study demonstrates that the current university reputation has a strong impact on the future reputation of its business school. These associations solidified from year to year which suggests practical implications for collaboration between university and business school administrators. Finally, this study explores how M.B.A. rankings affect funding streams to higher education institutions. Disentangling the differential impact of the rank of a business school on R&D funding coming to the university demonstrates positive associations between business school rankings and funding coming from the federal government and nonprofit organizations and negative associations between rankings and funding coming from the state and local government and institutional funds.
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    Technical characteristics of e-based vs. paper-pencil CBM tasks for students who are deaf and hard of hearing
    (2015-12) Lam, Elizabeth
    To increase literacy outcomes for students who are deaf and hard of hearing, professionals need to provide high quality instruction that is informed by accurate and valid assessment data. This study compared the reliability and validity of student scores from paper-pencil and e-based assessments, “Maze” and “Slash.” Forty (N=40) students, who were deaf or hard of hearing and read between the second and fifth grade reading level, participated. Twenty-one teachers of students who are deaf and hard of hearing also participated. For Maze, alternate form reliability coefficients obtained from correct scores and correct scores adjusted for guessing ranged from .61 to .84 (ps < .01); criterion-related validity ranged from .33 to .67 (majority of ps < .01). These findings are generally consistent with findings from previous research. For Slash, alternate form reliability coefficients obtained from correct scores ranged from .50 to .75 (ps < .01); criterion-related validity ranged from .25 to .72. The extent to which testing modifications delivered in an electronic-based (e-based) format influenced student scores was also examined. Differences between paper-pencil and e-based conditions were generally non-significant for Maze; significant differences between conditions for Slash favored the paper-pencil condition. Overall, findings suggest that Maze holds promise for use with students who are deaf and hard of hearing in both conditions, with inconclusive results for Slash. Future research is needed to explore the impact of providing testing modifications through e-based progress monitoring tools.
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    Validity of Electronic Prescription Claims Records: A Comparison of Commercial Insurance Claims with Pharmacy Provider Derived Records
    (University of Minnesota, College of Pharmacy, 2014) Martin, Bradley C.; Shewale, Anand
    Objectives: To determine if and to what extent records obtained from PBM pharmacy claims differ from source documents obtained directly from pharmacy providers. This study also sought to explore possible associations between patient, pharmacy benefits, and pharmacy provider characteristics and the likelihood a patient would have missing prescription claims. Methods: This study used a cross-sectional design which included a sample of 1,484 patients residing in a single state with a common pharmacy benefit. Profiles describing all prescriptions filled in a pharmacy between January 1, 2002 through June 30, 2002 of these patients were requested directly from their pharmacy providers. Logistic regression was used to explore the factors associated with a person receiving a prescription that did not appear on the PBM claims. Results: Of the 1,484 eligible recipients sampled, profiles were obtained for 323 (22%) persons and there were analyzable profiles for 315 (21%) persons. There were a total of 2,977 prescriptions filled for the 315 subjects. Of those 2,977 prescriptions, 207 (7.0%) were missing from the claims files indicating that 93% were captured. Only prescription volume consistently influenced the likelihood a patient would have a missing prescription from the PBM claims (OR =1.08; 95%CI:1.05-1.12). Conclusion: Claims obtained from pharmacy benefit companies capture approximately 93% of prescription records when verified with records obtained from pharmacy providers. The rate of missing records from PBM claims does not appear to be meaningfully influenced by most finance based pharmacy benefit design features. However, certain classes of drugs such as iron products, digoxins, diuretics, sulfonylureas, and antigout may have incomplete claims records compared to other classes of drugs. Higher prescription utilizers are more likely to have prescription records filled that are not captured by PBMs. These conclusions should be interpreted in light of the modest usable response rate from pharmacy providers of 22% and the unknown generalizability of these patients utilizing one particular PBM from 2002 in the state of Georgia.