Forecasting Some Low-Predictability Time Series Using Diffusion Indices

The growth rates of real output and real investment are two macroeconomic time series which are particularly difficult to forecast. This paper considers the application of diffusion index forecasting models to this problem. We begin by characterizing the performance of standard forecasts, via recently-introduced measures of predictability and the forecast content, noting the maximum horizon at which the forecasts have value. We then compare diffusion index forecasts with a variety of alternatives, including the forecasts made by the OECD. We find gains in forecast accuracy at short horizons from the diffusion index models, but do not find evidence that the maximum horizon for forecasts can be extended in this way. Les taux de croissance de production et d'investissements réels sont deux séries macroéconomiques qui sont particulièrement difficiles à prévoir. Nous considérons dans cet article l'application des méthodes d'indice de diffusion à ce problème. Nous commençons avec une caractérisation de la performance des méthodes de prévision standards, via les mesures nouvelles de prévisibilité et la valeur ajoutée des prévisions, en notant l'horizon maximal auquel les prévisions ont de la valeur. Nous comparons les prévisions provenant des indices de diffusion avec les alternatives, incluant les prévisions de l'OCDE. Nous trouvons des gains en précision des prévisions,0501s ne trouvons pas que l'horizon maximal de prévision peut être augmenté.Diffusion index, forecasting, investment, GDP, Indice de diffusion, prévisions, investissement, PNB

Forecasting Some Low-Predictability Time Series Using Diffusion Indices

Les taux de croissance de production et d'investissements réels sont deux séries macroéconomiques qui sont particulièrement difficiles à prévoir. Nous considérons dans cet article l'application des méthodes d'indice de diffusion à ce problème. Nous commençons avec une caractérisation de la performance des méthodes de prévision standards, via les mesures nouvelles de prévisibilité et la valeur ajoutée des prévisions, en notant l'horizon maximal auquel les prévisions ont de la valeur. Nous comparons les prévisions provenant des indices de diffusion avec les alternatives, incluant les prévisions de l'OCDE. Nous trouvons des gains en précision des prévisions,0501s ne trouvons pas que l'horizon maximal de prévision peut être augmenté.The growth rates of real output and real investment are two macroeconomic time series which are particularly difficult to forecast. This paper considers the application of diffusion index forecasting models to this problem. We begin by characterizing the performance of standard forecasts, via recently-introduced measures of predictability and the forecast content, noting the maximum horizon at which the forecasts have value. We then compare diffusion index forecasts with a variety of alternatives, including the forecasts made by the OECD. We find gains in forecast accuracy at short horizons from the diffusion index models, but do not find evidence that the maximum horizon for forecasts can be extended in this way

Cost-eff ectiveness of female human papillomavirus vaccination in 179 countries: a PRIME modelling study

Background Introduction of human papillomavirus (HPV) vaccination in settings with the highest burden of HPV is not universal, partly because of the absence of quantitative estimates of country-specifi c eff ects on health and economic costs. We aimed to develop and validate a simple generic model of such eff ects that could be used and understood in a range of settings with little external support. Methods We developed the Papillomavirus Rapid Interface for Modelling and Economics (PRIME) model to assess cost-eff ectiveness and health eff ects of vaccination of girls against HPV before sexual debut in terms of burden of cervical cancer and mortality. PRIME models incidence according to proposed vaccine effi cacy against HPV 16/18, vaccine coverage, cervical cancer incidence and mortality, and HPV type distribution. It assumes lifelong vaccine protection and no changes to other screening programmes or vaccine uptake. We validated PRIME against existing reports of HPV vaccination cost-eff ectiveness, projected outcomes for 179 countries (assuming full vaccination of 12-year-old girls), and outcomes for 71 phase 2 GAVI-eligible countries (using vaccine uptake data from the GAVI Alliance). We assessed diff erences between countries in terms of cost-eff ectiveness and health eff ects. Findings In validation, PRIME reproduced cost-eff ectiveness conclusions for 24 of 26 countries from 17 published studies, and for all 72 countries in a published study of GAVI-eligible countries. Vaccination of a cohort of 58 million 12-year-old girls in 179 countries prevented 690 000 cases of cervical cancer and 420 000 deaths during their lifetime (mostly in low-income or middle-income countries), at a net cost of US$4 billion. HPV vaccination was very cost eff ective (with every disability-adjusted life-year averted costing less than the gross domestic product per head) in 156 (87%) of 179 countries. Introduction of the vaccine in countries without national HPV vaccination at present would prevent substantially more cases of cervical cancer than in countries with such programmes, although the disparity has narrowed since 2012. If 71 phase 2 GAVI-eligible countries adopt vaccination according to forecasts, then in 2070 GAVI Alliance-funded vaccination could prevent 200 000 cases of cervical cancer and 100 000 deaths in some of the highest-burden countries. Interpretation Large between-country disparities exist for HPV vaccination, with countries with the most to gain yet to introduce national HPV vaccination. Support from the GAVI Alliance could help to reduce such disparities, but a substantial burden will remain even after presently projected vaccine introductions

Economic Evaluation of Vaccination Programmes: A Special Reference to Varicella Vaccination

The thesis has two broad aims. The first aim is to evaluate the effectiveness and “cost-effectiveness” of routine childhood varicella vaccination in the UK. To do so, a deterministic realistic age-structured model was built which incorporated herd- immunity effects and the indirect impact of varicella vaccination on zoster. The model predicts that although the overall morbidity due to varicella is likely to decrease following infant vaccination, these benefits will be offset by a significantly increase in zoster cases. These modelling results were used to explore the possible economic desirability of mass varicella vaccination. To do so, we perform the three major types of economic evaluation. The economic analysis predicts that using cost-utility and cost-effectiveness analysis, routine infant varicella vaccination is unlikely to be ’’cost- effective” and may produce an overall increase in morbidity. On the other hand, varicella is highly cost-beneficial when using £ as the outcome measure. Finally, we show that results are less sensitive to parameter estimates than model and methodological assumptions The second aim of the thesis is to address the major methodological issues related to the economic evaluation of vaccination programs using varicella vaccination as an example. Firstly, we compare results from a dynamic model with those of a static model to illustrate the impact of including herd-immunity and to help provide guidance on which model should be used when assessing the impact of vaccination. Secondly, we assess the average willingness to pay for varicella vaccination and the QALY lost due to chickenpox using various elicitation techniques. We then identify important attributes of vaccination and what elicitation techniques can capture these components. Results are compared to investigate what valuation techniques should be used in the economic evaluation of vaccine programmes. Thirdly, we assess the sensitivity of economic analysis to the choice of model, methodological assumptions and parameter estimates. Finally, we propose guidelines for the economic evaluation of vaccination programmes based on the various findings of the thesis

Model Comparisons of the Effectiveness and Cost-Effectiveness of Vaccination: A Systematic Review of the Literature.

OBJECTIVES: To describe all published articles that have conducted comparisons of model-based effectiveness and cost-effectiveness results in the field of vaccination. Specific objectives were to 1) describe the methodologies used and 2) identify the strengths and limitations of the studies. METHODS: We systematically searched MEDLINE and Embase databases for studies that compared predictions of effectiveness and cost-effectiveness of vaccination of two or more mathematical models. We categorized studies into two groups on the basis of their data source for comparison (previously published results or new simulation results) and performed a qualitative synthesis of study conclusions. RESULTS: We identified 115 eligible articles (only 5% generated new simulations from the reviewed models) examining the effectiveness and cost-effectiveness of vaccination against 14 pathogens (69% of studies examined human papillomavirus, influenza, and/or pneumococcal vaccines). The goal of most of studies was to summarize evidence for vaccination policy decisions, and cost-effectiveness was the most frequent outcome examined. Only 33%, 25%, and 3% of studies followed a systematic approach to identify eligible studies, assessed the quality of studies, and performed a quantitative synthesis of results, respectively. A greater proportion of model comparisons using published studies followed a systematic approach to identify eligible studies and to assess their quality, whereas more studies using new simulations performed quantitative synthesis of results and identified drivers of model conclusions. Most comparative modeling studies concluded that vaccination was cost-effective. CONCLUSIONS: Given the variability in methods used to conduct/report comparative modeling studies, guidelines are required to enhance their quality and transparency and to provide better tools for decision making

Comparison of two dose and three dose human papillomavirus vaccine schedules: cost effectiveness analysis based on transmission model.

OBJECTIVE: To investigate the incremental cost effectiveness of two dose human papillomavirus vaccination and of additionally giving a third dose. DESIGN: Cost effectiveness study based on a transmission dynamic model of human papillomavirus vaccination. Two dose schedules for bivalent or quadrivalent human papillomavirus vaccines were assumed to provide 10, 20, or 30 years' vaccine type protection and cross protection or lifelong vaccine type protection without cross protection. Three dose schedules were assumed to give lifelong vaccine type and cross protection. SETTING: United Kingdom. POPULATION: Males and females aged 12-74 years. INTERVENTIONS: No, two, or three doses of human papillomavirus vaccine given routinely to 12 year old girls, with an initial catch-up campaign to 18 years. MAIN OUTCOME MEASURE: Costs (from the healthcare provider's perspective), health related utilities, and incremental cost effectiveness ratios. RESULTS: Giving at least two doses of vaccine seems to be highly cost effective across the entire range of scenarios considered at the quadrivalent vaccine list price of £86.50 (€109.23; $136.00) per dose. If two doses give only 10 years' protection but adding a third dose extends this to lifetime protection, then the third dose also seems to be cost effective at £86.50 per dose (median incremental cost effectiveness ratio £17,000, interquartile range £11,700-£25,800). If two doses protect for more than 20 years, then the third dose will have to be priced substantially lower (median threshold price £31, interquartile range £28-£35) to be cost effective. Results are similar for a bivalent vaccine priced at £80.50 per dose and when the same scenarios are explored by parameterising a Canadian model (HPV-ADVISE) with economic data from the United Kingdom. CONCLUSIONS: Two dose human papillomavirus vaccine schedules are likely to be the most cost effective option provided protection lasts for at least 20 years. As the precise duration of two dose schedules may not be known for decades, cohorts given two doses should be closely monitored

Desarrollo de la inhibición: comparación de medidas neuropsicológicas y de seguimiento de ojos

Inhibition is the ability to stop an automatic response when a stimulus is presented. It is one main component of executive function models. Few studies have evaluated the development of this ability’s in children between five and eight years of age using eye tracking measures. The first objective of this exploratory study is to evaluate the performance difference of younger compared to older children. The second objective is to evaluate if inhibition assessed via three different neuropsychological tests develops at a similar rate as inhibition assessed via two eye tracking tasks. Forty-six children aged 5.7 to 8.4 years completed both types of tests. Results show that one neuropsychological test was sensitive to the children’ increasing inhibition ability, while both eye tracking tests were. Additionally, scores from one eye tracking task correlated with scores from one neuropsychological test. Possible explanations of moderate relations between tasks are discussed.La inhibición es la capacidad de detener una respuesta automática. Es una de las funciones ejecutivas principales. Pocos estudios han evaluado su desarrollo en niños de cinco a ocho años utilizando pruebas de seguimiento de ojos. Este estudio exploratorio tiene, como primer objetivo, evaluar la diferencia de rendimiento entre los más jóvenes y los mayores. El segundo objetivo es evaluar si la inhibición se desarrolla a un ritmo similar en tres pruebas neuropsicológicas y dos pruebas de seguimiento de ojos. Cuarenta y seis niños, de 5 años y 8 meses a 8 años y 5 meses, realizaron ambos tipos de pruebas. Los resultados muestran que una de las pruebas neuropsicológicas y ambas pruebas de seguimiento de ojos fueron sensibles a la mejora de la inhibición. Además, resultados de una prueba de seguimiento de ojos y de una prueba neuropsicológica estaban correlacionados. Se discuten las explicaciones posibles de las relaciones entre las tareas

Human papillomavirus vaccine effectiveness by number of doses: Systematic review of data from national immunization programs.

BACKGROUND: Human papillomavirus (HPV) vaccines were first licensed as a three-dose series; a two-dose series is now recommended in some age groups and there is interest in possible one-dose vaccination. METHODS: We conducted a systematic literature review of HPV vaccine effectiveness by number of doses, including assessment of biases and impact of varying buffer periods (time between vaccination and outcome counting). RESULTS: Of 3787 articles identified, 26 full articles were assessed and 14 included in our review. All studies were conducted within the context of recommended three-dose schedules of bivalent (3) or quadrivalent HPV vaccine (11). Two evaluated effectiveness for prevention of HPV prevalence, six anogenital warts, and six abnormal cervical cytology or histology. Many studies found differences between three-, two- and one-dose vaccine recipients, indicating possible differences in HPV exposure prior to vaccination or in risk behavior. Adjusted or stratified analyses were conducted to control for potential confounding. All studies found significant vaccine effectiveness with three doses, 11 with two doses at various intervals, and six with one dose. Most studies showed a relationship (not always statistically significant) between effectiveness and number of doses, with greater decreases in HPV-related outcomes with three, followed by two and one dose(s). Few studies conducted formal comparisons of three vs fewer doses. Three of four studies that examined buffer periods found higher effectiveness and a smaller difference by number of doses with longer periods. CONCLUSION: Most post-licensure studies report highest effectiveness with three doses; some found no statistically significant difference between two and three doses. Additionally, almost half found some effectiveness with one dose. Several biases impact estimates, with most biasing two- and one-dose results away from showing effectiveness. Future effectiveness studies, examining persons vaccinated prior to sexual activity and using methods to reduce potential sources of bias, can help inform vaccination policy

Synthesis of Pyridinium Amphiphiles Used for Transfection and Some Characteristics of Amphiphile/DNA Complex Formation

Pyridinium amphiphiles have found practical use for the delivery of DNA into cells. Starting from 4-methylpyridine, a general synthesis has been devised for the production of pyridinium amphiphiles which allows variation in both the hydrophobic part and in the headgroup area of the compounds. By means of differential scanning microcalorimetry, zeta potential, particle size measurements and cryo electron microscopy, some characteristics of the pyridinium amphiphile/ DNA complexes have been determined.