Comparison of Nonlinear Spatial Correlation Models by the Influence of the Data Augmentation to the Classification Risk

The Bayesian classification rule used for the classification of the observations of the (second-order) stationary Gaussian random fields with different means and common factorised covariance matrices is investigated. The influence of the observed data augmentation to the Bayesian risk is examined for three different nonlinear widely applicable spatial correlation models. The explicit expression of the Bayesian risk for the classification of augmented data is derived. Numerical comparison of these models by the variability of Bayesian risk in case of the first-order neighbourhood scheme is performed

Quadratic Discriminant Analysis of Spatially Correlated Data

The problem of classification of the realisation of the stationary univariate Gaussian random field into one of two populations with different means and different factorised covariance matrices is considered. In such a case optimal classification rule in the sense of minimum probability of misclassification is associated with non-linear (quadratic) discriminant function. Unknown means and the covariance matrices of the feature vector components are estimated from spatially correlated training samples using the maximum likelihood approach and assuming spatial correlations to be known. Explicit formula of Bayes error rate and the first-order asymptotic expansion of the expected error rate associated with quadratic plug-in discriminant function are presented. A set of numerical calculations for the spherical spatial correlation function is performed and two different spatial sampling designs are compared

Implementing structured functional assessments in general practice for persons with long-term sick leave: a cluster randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>The increasing attention on functional assessments in medical and vocational rehabilitation requires a focus change for the general practitioners (GP) into paying attention to patient resources, possibilities and coping instead of symptoms, problems and limitations. The GPs report difficulties in performing the requested explicit functional assessments. The purpose of this study was to implement a structured method in general practice for assessing functional ability in persons with long-term sick leave. The study aim was to evaluate intervention effects on important GP parameters; knowledge, attitudes, self-efficacy towards functional assessments and knowledge about patient work factors.</p> <p>Methods</p> <p>Fifty-seven GPs were randomly assigned to an intervention or a control group. The intervention group GPs attended an introductory one-day work-shop and implemented structured functional assessments during an eight months intervention period. GP knowledge, GP attitudes, and GP self-efficacy towards functional assessments, as well as GP knowledge of patient work factors, were collected before, after and six months after the intervention period started. Evaluation score-sheets were filled in by both the intervention GPs and their patients immediately after the consultation to evaluate the GPs' knowledge of patient work factors.</p> <p>Results</p> <p>The intervention GPs reported increased knowledge (B: 0.56, 95% CI (0.19, 0.91)) and self-efficacy (B: 0.90, 95% CI (0.53, 1.26)) towards functional assessments, and increased knowledge about their patients' workplace (B: 0.75, 95% CI (0.35, 1.15)) and perceived stressors (B: 0.55, 95% CI (0.23, 0.88)) with lasting effects at the second follow-up. No intervention effect was seen in relation to GP attitudes. Both before and after the intervention, the GPs were most informed about physical stressors, and less about mental and work organisational stressors (Guttman's reproducibility coefficient: 0.95 and 1.00). After the consultation, both the intervention GPs and their patients reported that the GPs' knowledge about patient work factors had increased (GP B: 0.60 (95% CI: 0.42, 0.78); patient B: 0.50 (95% CI: 0.34, 0.66)).</p> <p>Conclusion</p> <p>Introducing and implementing structured functional assessments in general practice made the GPs capable to assess functional ability of their patients in a structured manner. Intervention effects of increased GP knowledge and GP self-efficacy sustained at the second follow-up.</p

Modelling and prediction of weekly incidence of influenza A specimens in England and Wales

We propose a rather simple model, which fits well the weekly human influenza incidence data from England and Wales. A standard way to analyse seasonally varying time-series is to decompose them into different components. The residuals obtained after eliminating these components often do not reveal time dependency and are normally distributed. We suggest that conclusions should not be drawn only on the basis of residuals and that one should consider the analysis of squared residuals. We show that squared residuals can reveal the presence of the remaining seasonal variation, which is not exhibited by the analysis of residuals, and that the modelling of such seasonal variations undoubtedly improves model fit

A cross-sectional population-based survey of migraine and headache in 21,177 Norwegians: the Akershus sleep apnea project

The objective was to investigate the prevalence and interrelation of migraine and headache in the general population. Forty thousand men and women aged 20–80 years from the Norwegian general population received a mailed questionnaire with questions about migraine and headache. The questionnaire response rate was 54.5%. The lifetime prevalence of migraine was 26.5% (95% CI 25.9–27.1%), i.e., 18.1% (95% CI 17.3–18.9%) in men and 34.1% (95% CI 33.2–35.0%) in women. The prevalence of migraine decreased slightly in both men and women after an age of 45. The 1 year prevalence of headache was 77.2%, i.e., 69.6% (95% CI 68.7–70.6%) in men and 84.0% (95% CI 83.3–84.7%) in women. The frequency of headache decreased with age, but some of the elders aged 70 or above experienced more frequent headache. The prevalence of being headache free increased from 19.1% (95% CI 14.2–25.6%) to 74.7% (95% CI 70.0–78.8%) in 20 and 80 years old men without co-occurrence of migraine, and from 5.1% (95% CI 2.9–8.8%) to 61.4% (95% CI 54.9–67.6%) in 20 and 80 years old women without co-occurrence of migraine. Co-occurrence of migraine significantly increased the frequency of headache and decreased the prevalence of being headache free. Published Open Access with SpringerOpe