Doctor of Philosophy

dissertationA review of traditional mathematics instruction suggests that conventional methods emphasize student learning of declarative rules about math problem solving procedures, especially in the early phase of learning. In contrast to the implicit learning of procedural skills, this approach places heavy demands on working memory and may be partly responsible for low levels of math achievement by many students. The present study explored the plausibility of implicit learning of polynomial problem structure prior to declarative rule instruction and its impact on subsequent problem solving skill, rule learning, and perception of difficulty. Participants selected proper factorizations of quadratic polynomials from two possible answer choices over many blocks in a task that was structured to achieve errorless learning through a vanishing cues approach. Measures were administered to assess problem solving skill, rule understanding, and perception of learning difficulty. Evidence supports the hypothesis that some mathematics skill can be learned implicitly, but marginal and conflicting results raise questions about the impact of initial implicit learning on subsequent rule learning and difficulty perception. Findings are interpreted with respect to implicit learning and skill acquisition theories

Tjenestedesign, et egnet verktøy for næringsutvikling i offentlig sektor?

Oppgaven er en casestudie av Lebesby og Skjervøy kommune. Begge kommunene har vært med i Gnist-programmet som en innovkasjonskonkurranse for næringsutvikling i samarbeid med DOGA og Nordic Egde. Vinner av konkurransene har vært Plenum tjenestedesign som har levert de ferdige prosjektene til hver sin kommune. I denne oppgaven har jeg sett på bakgrunnen for søknaden og hva som kan forklare utfallet av prosessene. Problemstillingen min i oppgaven har vært: Hvorfor valgte Skjervøy og Lebesby kommune å søke på Gnist-programmet, hva kan forklare implementeringen så lang, og hva ble resultatet

A new formula for fast computation of segmented cross validation residuals in linear regression modelling -- providing efficient regularisation parameter estimation in Ridge Regression and the Tikhonov Regularisation Framework

In the present paper we prove a new theorem, resulting in an exact updating formula for linear regression model residuals to calculate the segmented cross-validation residuals for any choice of cross-validation strategy without model refitting. The required matrix inversions are limited by the cross-validation segment sizes and can be executed with high efficiency in parallel. The well-known formula for leave-one-out cross-validation follows as a special case of our theorem. In situations where the cross-validation segments consist of small groups of repeated measurements, we suggest a heuristic strategy for fast serial approximations of the cross-validated residuals and associated PRESS statistic. We also suggest strategies for quick estimation of the exact minimum PRESS value and full PRESS function over a selected interval of regularisation values. The computational effectiveness of the parameter selection for Ridge-/Tikhonov regression modelling resulting from our theoretical findings and heuristic arguments is demonstrated for several practical applications.Comment: 33 pages, 10 figure, 8 table

Orders of magnitude speed increase in Partial Least Squares feature selection with new simple indexing technique for very tall data sets

Feature selection is a challenging combinatorial optimization problem that tends to require a large number of candidate feature subsets to be evaluated before a satisfying solution is obtained. Because of the computational cost associated with estimating the regression coefficients for each subset, feature selection can be an immensely time-consuming process and is often left inadequately explored. Here, we propose a simple modification to the conventional sequence of calculations involved when fitting a number of feature subsets to the same response data with partial least squares (PLS) model fitting. The modification consists in establishing the covariance matrix for the full set of features by an initial calculation and then deriving the covariance of all subsequent feature subsets solely by indexing into the original covariance matrix. By choosing this approach, which is primarily suitable for tall design matrices with significantly more rows than columns, we avoid redundant (identical) recalculations in the evaluation of different feature subsets. By benchmarking the time required to solve regression problems of various sizes, we demonstrate that the introduced technique outperforms traditional approaches by several orders of magnitude when used in conjunction with PLS modeling. In the supplementary material, we provide code for implementing the concept with kernel PLS regression.acceptedVersio

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Master i bedriftsledelse (MBA) - 201

Work and mental complaints: are response outcome expectancies more important than work conditions and number of subjective health complaints?

Purpose Investigate the relative effect of response outcome expectancies, work conditions, and number of subjective health complaints (SHC) on anxiety and depression in Norwegian employees. Learned response outcome expectancies are important contributors to health. Individual differences in the expectancy to cope with workplace and general life demands may be important for how work conditions influence health. Method A survey was conducted among 1746 municipal employees (mean age 44.1, SD = 11.5, 81.5 % female), as part of a randomized controlled trial. This cross-sectional study used baseline data. Multiple logistic regression analysis was performed. Outcome variables were anxiety and depression; response outcome expectancies, work conditions, and number of SHC were independent variables. Results A high number of SHC was a significant factor in explaining anxiety (OR 1.26), depression (OR 1.22) and comorbid anxiety and depression (OR 1.31). A high degree of no and/or negative response outcome expectancies was a significant factor in explaining depression (OR 1.19) and comorbid anxiety and depression (OR 1.28). The variance accounted for in the full models was 14 % for anxiety, 23 % for depression, and 41 % for comorbid anxiety and depression. Conclusion A high number of SHC, and a high degree of no and/or negative response outcome expectancies were associated with anxiety and depression. The strongest association was found for number of SHC. However, previous studies indicate that it may not be possible to prevent the occurrence of SHC. We suggest that workplace interventions targeting anxiety and depression could focus on influencing and altering employees’ response outcome expectancies.publishedVersio

An educational approach based on a non-injury model compared with individual symptom-based physical training in chronic LBP. A pragmatic, randomised trial with a one-year follow-up

<p>Abstract</p> <p>Background</p> <p>In the treatment of chronic back pain, cognitive methods are attracting increased attention due to evidence of effectiveness similar to that of traditional therapies. The purpose of this study was to compare the effectiveness of performing a cognitive intervention based on a non-injury model with that of a symptom-based physical training method on the outcomes of low back pain (LBP), activity limitation, LBP attitudes (fear-avoidance beliefs and back beliefs), physical activity levels, sick leave, and quality of life, in chronic LBP patients.</p> <p>Methods</p> <p>The study was a pragmatic, single-blind, randomised, parallel-group trial. Patients with chronic/recurrent LBP were randomised to one of the following treatments: 1. <it>Educational programme </it>: the emphasis was on creating confidence that the back is strong, that loads normally do not cause any damage despite occasional temporary pain, that reducing the focus on the pain might facilitate more natural and less painful movements, and that it is beneficial to stay physically active. 2. <it>Individual symptom-based physical training programme </it>: directional-preference exercises for those centralising their pain with repetitive movements; 'stabilising exercises' for those deemed 'unstable' based on specific tests; or intensive dynamic exercises for the remaining patients. Follow-up questionnaires (examiner-blinded) were completed at 2, 6 and 12 months. The main statistical test was an ANCOVA adjusted for baseline values.</p> <p>Results</p> <p>A total of 207 patients participated with the median age of 39 years (IQR 33-47); 52% were female, 105 were randomised to the educational programme and 102 to the physical training programme. The two groups were comparable at baseline. For the primary outcome measures, there was a non-significant trend towards activity limitation being reduced mostly in the educational programme group, although of doubtful clinical relevance. Regarding secondary outcomes, improvement in fear-avoidance beliefs was also better in the educational programme group. All other variables were about equally influenced by the two treatments. The median number of treatment sessions was 3 for the educational programme group and 6 for the physical training programme group.</p> <p>Conclusions</p> <p>An educational approach to treatment for chronic LBP resulted in at least as good outcomes as a symptom-based physical training method, despite fewer treatment sessions.</p> <p>Trial registration</p> <p>Clinicaltrials.gov: # NCT00410319</p