Estimating Yield Curves by Kernel Smoothing Methods

We introduce a new method for the estimation of discount functions, yield curves and forward curves for coupon bonds. Our approach is nonparametric and does not assume a particular functional form for the discount function although we do show how to impose various important restrictions in the estimation. Our method is based on kernel smoothing and is defined as the minimum of some localized population moment condition. The solution to the sample problem is not explicit and our estimation procedure is iterative, rather like the backfitting method of estimating additive nonparametric models. We establish the asymptotic normality of our methods using the asymptotic representation of our estimator as an infinite series with declining coefficients. The rate of convergence is standard for one dimensional nonparametric regression.Coupon bonds; forward curve; Hilbert space; local linear; nonparametric regression; yield curve

Yield Curve Estimation by Kernel Smoothing Methods

We introduce a new method for the estimation of discount functions, yield curves and forward curves from government issued coupon bonds. Our approach is nonparametric and does not assume a particular functional form for the discount function although we do show how to impose various restrictions in the estimation. Our method is based on kernel smoothing and is defined as the minimum of some localized population moment condition. The solution to the sample problem is not explicit and our estimation procedure is iterative, rather like the backfitting method of estimating additive nonparametric models. We establish the asymptotic normality of our methods using the asymptotic representation of our estimator as an infinite series with declining coefficients. The rate of convergence is standard for one dimensional nonparametric regression. We investigate the finite sample performance of our method, in comparison with other well-established methods, in a small simulation experiment.Coupon bonds, kernel estimation, Hilbert space, nonparametric regression, term structure estimation, yield curve, zero coupon.

The Earned Income Tax Credit and Rural Families: Differences between Participants and Non-participants

The differences between rural low-income mothers who were participants and non-participants in the Earned Income Tax Credit (EITC) were examined. One-third of the 224 eligible mothers in a multi-state study did not claim the tax credit. Non-participants were more likely to be Hispanic, less educated, with larger families, borrowing money from family, and living in more rural counties. Participating mothers, on the other hand, were more food secure, perceived their household income as being adequate, reported recent improvements in their economic situation, were satisfied with life, and lived in states with a state EITC. Analysis of qualitative data revealed that rural mothers had many misconceptions about the EITC. These findings contribute to family and economic professionals’ understanding of why rural low-income families do not participate in the tax credit and assist in formulating policies and education/outreach efforts that would increase their participationEITC non-participants, EITC participants, rural low-income mothers, state EITC, rural low-income families

Spatial and temporal clustering of dengue virus transmission in Thai villages.

BackgroundTransmission of dengue viruses (DENV), the leading cause of arboviral disease worldwide, is known to vary through time and space, likely owing to a combination of factors related to the human host, virus, mosquito vector, and environment. An improved understanding of variation in transmission patterns is fundamental to conducting surveillance and implementing disease prevention strategies. To test the hypothesis that DENV transmission is spatially and temporally focal, we compared geographic and temporal characteristics within Thai villages where DENV are and are not being actively transmitted.Methods and findingsCluster investigations were conducted within 100 m of homes where febrile index children with (positive clusters) and without (negative clusters) acute dengue lived during two seasons of peak DENV transmission. Data on human infection and mosquito infection/density were examined to precisely (1) define the spatial and temporal dimensions of DENV transmission, (2) correlate these factors with variation in DENV transmission, and (3) determine the burden of inapparent and symptomatic infections. Among 556 village children enrolled as neighbors of 12 dengue-positive and 22 dengue-negative index cases, all 27 DENV infections (4.9% of enrollees) occurred in positive clusters (p < 0.01; attributable risk [AR] = 10.4 per 100; 95% confidence interval 1-19.8 per 100]. In positive clusters, 12.4% of enrollees became infected in a 15-d period and DENV infections were aggregated centrally near homes of index cases. As only 1 of 217 pairs of serologic specimens tested in positive clusters revealed a recent DENV infection that occurred prior to cluster initiation, we attribute the observed DENV transmission subsequent to cluster investigation to recent DENV transmission activity. Of the 1,022 female adult Ae. aegypti collected, all eight (0.8%) dengue-infected mosquitoes came from houses in positive clusters; none from control clusters or schools. Distinguishing features between positive and negative clusters were greater availability of piped water in negative clusters (p < 0.01) and greater number of Ae. aegypti pupae per person in positive clusters (p = 0.04). During primarily DENV-4 transmission seasons, the ratio of inapparent to symptomatic infections was nearly 1:1 among child enrollees. Study limitations included inability to sample all children and mosquitoes within each cluster and our reliance on serologic rather than virologic evidence of interval infections in enrollees given restrictions on the frequency of blood collections in children.ConclusionsOur data reveal the remarkably focal nature of DENV transmission within a hyperendemic rural area of Thailand. These data suggest that active school-based dengue case detection prompting local spraying could contain recent virus introductions and reduce the longitudinal risk of virus spread within rural areas. Our results should prompt future cluster studies to explore how host immune and behavioral aspects may impact DENV transmission and prevention strategies. Cluster methodology could serve as a useful research tool for investigation of other temporally and spatially clustered infectious diseases

Primary healthcare policy and vision for community pharmacy and pharmacists in Germany.

Germany is the highest populated country in Europe with a population of 82.3 million in 2019. As in many other developed countries, it has an aging population. Approximately 10% of the gross domestic product is spent on healthcare. The healthcare system is characterized by its accessibility. Patients are generally free to choose their primary care physicians, both family doctors and specialists, pharmacy, dentist, or emergency service. Up to a certain income, health insurance is mandatory with the statutory health insurance (SHI) system, covering 88% of the population. Major challenges are the lack of cooperation and integration between the different sectors and healthcare providers. This is expected to change with the introduction of a telematic infrastructure that is currently being implemented. It will not only connect all providers in primary and secondary care in a secure network but will also enable access to patients' electronic record/medical data and at the same time switch from paper to electronic prescriptions. Approximately 52,000 of the 67,000 pharmacists are working in approximately 19,000 community pharmacies. These pharmacies are owner-operated by a pharmacist. Pharmacists may own up to three subsidiaries nearby to their main pharmacy. Community pharmacy practice mainly consists of dispensing drugs, counselling patients on drug therapy and safety, and giving advice on lifestyle and healthy living. Many cognitive pharmaceutical services have been developed and evaluated in the past 20 years. Discussions within the profession and with stakeholders on the national level on the roles and responsibilities of pharmacists have resulted in nationally agreed guidelines, curricula, and services. However, cognitive services remunerated by the SHI funds on the national level remain to be negotiated and sustainably implemented. A law passed in November 2020 by parliament will regulate the remuneration of pharmaceutical services by the SHI funds with an annual budget of EUR 150 million. The type of services and their remuneration remain to be negotiated in 2021. The profession has to continue on all levels to advocate for a change in pharmacy practice by introducing pharmacy services into routine care

Molecular basis of hereditary factor VII deficiency in India: five novel mutations including a double missense mutation (Ala191Glu; Trp364Cys) in 11 unrelated patients

We have studied the molecular basis of factor (F) VII deficiency in 11 unrelated Indian patients. Mutations were identified in all 11 and included 5 missense, 2 nonsense and a frame shift mutation. Five of these were novel. These mutations were considered to be causative of disease because of their nature, evolutionary conservation and molecular modeling. This is the first report of mutations in patients with FVII deficiency from southern India

PAC-Bayesian Bounds for Randomized Empirical Risk Minimizers

The aim of this paper is to generalize the PAC-Bayesian theorems proved by Catoni in the classification setting to more general problems of statistical inference. We show how to control the deviations of the risk of randomized estimators. A particular attention is paid to randomized estimators drawn in a small neighborhood of classical estimators, whose study leads to control the risk of the latter. These results allow to bound the risk of very general estimation procedures, as well as to perform model selection

Frequent In-Migration and Highly Focal Transmission of Dengue Viruses Among Children in Kamphaeng Phet, Thailand

Revealing the patterns and determinants of the spread of dengue virus (DENV) at local scales is central to understanding the epidemiology and evolution of this major human pathogen. We performed a phylogenetic analysis of the envelope (E) genes of DENV-1, -2, -3, and -4 isolates (involving 97, 23, 5, and 74 newly collected sequences, respectively) sampled from school-based cohort and village-based cluster studies in Kamphaeng Phet, Thailand, between 2004 and 2007. With these data, we sought to describe the spatial and temporal patterns of DENV spread within a rural population where a future vaccine efficacy trial is planned. Our analysis revealed considerable genetic diversity within the study population, with multiple lineages within each serotype circulating for various lengths of time during the study period. These results suggest that DENV is frequently introduced into both semi-urban and rural areas in Kamphaeng Phet from other populations. In contrast, the persistence of viral lineages across sampling years was observed less frequently. Analysis of phylogenetic clustering indicated that DENV transmission was highly spatially and temporally focal, and that it occurred in homes rather than at school. Overall, the strength of temporal clustering suggests that seasonal bottlenecks in local DENV populations facilitate the invasion and establishment of viruses from outside of the study area, in turn reducing the extent of lineage persistence

A Path Algorithm for Constrained Estimation

Many least squares problems involve affine equality and inequality constraints. Although there are variety of methods for solving such problems, most statisticians find constrained estimation challenging. The current paper proposes a new path following algorithm for quadratic programming based on exact penalization. Similar penalties arise in $l_1$ regularization in model selection. Classical penalty methods solve a sequence of unconstrained problems that put greater and greater stress on meeting the constraints. In the limit as the penalty constant tends to $\infty$, one recovers the constrained solution. In the exact penalty method, squared penalties are replaced by absolute value penalties, and the solution is recovered for a finite value of the penalty constant. The exact path following method starts at the unconstrained solution and follows the solution path as the penalty constant increases. In the process, the solution path hits, slides along, and exits from the various constraints. Path following in lasso penalized regression, in contrast, starts with a large value of the penalty constant and works its way downward. In both settings, inspection of the entire solution path is revealing. Just as with the lasso and generalized lasso, it is possible to plot the effective degrees of freedom along the solution path. For a strictly convex quadratic program, the exact penalty algorithm can be framed entirely in terms of the sweep operator of regression analysis. A few well chosen examples illustrate the mechanics and potential of path following.Comment: 26 pages, 5 figure

Pharmacy-based interdisciplinary intervention for patients with chronic heart failure: results of the PHARM-CHF randomized controlled trial.

AIMS:Medication non-adherence is frequent and is associated with high morbidity and mortality in patients with chronic heart failure (CHF). We investigated whether an interdisciplinary intervention improves adherence in elderly CHF patients. METHODS AND RESULTS:The study population (mean age 74 years, 62% male, mean left ventricular ejection fraction 47%, 52% in New York Heart Association class III) consisted of 110 patients randomized into the pharmacy care and 127 into the usual care group. The median follow-up was 2.0 years (interquartile range 1.2-2.7). The pharmacy care group received a medication review followed by regular dose dispensing and counselling. Control patients received usual care. The primary endpoint was medication adherence as proportion of days covered (PDC) within 365 days for three classes of heart failure medications (beta-blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and mineralocorticoid receptor antagonists). The main secondary outcome was the proportion of adherent patients (PDC ≥ 80%). The primary safety endpoint was days lost due to unplanned cardiovascular hospitalizations (blindly adjudicated) or death. Pharmacy care compared with usual care resulted in an absolute increase in mean adherence to three heart failure medications for 365 days [adjusted difference 5.7%, 95% confidence interval (CI) 1.6-9.8, P = 0.007]. The proportion of patients classified as adherent increased (odds ratio 2.9, 95% CI 1.4-5.9, P = 0.005). Pharmacy care improved quality of life after 2 years (adjusted difference in Minnesota Living with Heart Failure Questionnaire scores -7.8 points (-14.5 to -1.1; P = 0.02), compared to usual care. Pharmacy care did not affect the safety endpoints of hospitalizations or deaths. CONCLUSION:Pharmacy care safely improved adherence to heart failure medications and quality of life