A comparison of in-sample forecasting methods

In-sample forecasting is a recent continuous modification of well-known forecasting methods based on aggregated data. These aggregated methods are known as age-cohort methods in demography, economics, epidemiology and sociology and as chain ladder in non-life insurance. Data is organized in a two-way table with age and cohort as indices, but without measures of exposure. It has recently been established that such structured forecasting methods based on aggregated data can be interpreted as structured histogram estimators. Continuous in-sample forecasting transfers these classical forecasting models into a modern statistical world including smoothing methodology that is more efficient than smoothing via histograms. All in-sample forecasting estimators are collected and their performance is compared via a finite sample simulation study. All methods are extended via multiplicative bias correction. Asymptotic theory is being developed for the histogram-type method of sieves and for the multiplicatively corrected estimators. The multiplicative bias corrected estimators improve all other known in-sample forecasters in the simulation study. The density projection approach seems to have the best performance with forecasting based on survival densities being the runner-up

In-Sample Forecasting Applied to Reserving and Mesothelioma Mortality

This paper shows that recent published mortality projections with unobserved exposure can be understood as structured density estimation. The structured density is only observed on a sub-sample corresponding to historical calendar time. The mortality forecast is obtained by extrapolating the structured density to future calendar times using that the components of the density are identified within sample. The new method is illustrated on the important practical problem of forecasting mesothelioma for the UK population. Full asymptotic theory is provided. The theory is given in such generality that it also introduces mathematical statistical theory for the recent continuous chain ladder model. This allows a modern approach to classical reserving techniques used every day in any non-life insurance company around the globe. Applications to mortality data and non-life insurance data are provided along with relevant small sample simulation studies

Interdisciplinary Physician-Pharmacist Medication Review for Outpatients With Heart Failure: A Subanalysis of the PHARM-CHF Randomized Controlled Trial.

Aims: Patients with chronic heart failure (CHF) require polypharmacy and are at increased risk for drug-related problems. Interdisciplinary physician-pharmacist medication review may improve drug treatment. Our goal was to analyze the changes from the physician-documented medication plan (MP) and patient-stated medication to an interdisciplinary consolidated MP (CMP). Methods: This pre-specified subanalysis of the PHARM-CHF randomized controlled trial analyzed the medication review of CHF patients in the pharmacy care group. Community pharmacists compared the MP with the drug regimen stated by the patient and consulted with physicians on identified discrepancies and other medication-related problems resulting in a CMP. Results: We analyzed 93 patients (mean 74.0 ± 6.6 years, 37.6% female), taking a median of ten (IQR 8-13) drugs. 80.6% of patients had at least one change from MP to CMP. We identified changes in 32.7% (303/926) of drugs. The most common correction was the addition of a drug not documented in the MP to the CMP (43.2%). We also determined frequent modifications in the dosing regimens (37.6%). The omission of a drug documented in the MP but left out of the CMP accounted for 19.1%. Comparing patient-stated medication to CMP, the current drug regimen of patients was changed in 22.4% of drugs. Conclusion: The medication review resulted in changes of medication between MP and CMP in most of the patients and affected one-third of drugs. Structured physician-pharmacist interdisciplinary care is able to harmonize and optimize the drug treatment of CHF patients

Pre-transplant reduction of isohaemagglutinin titres by donor group plasma infusion does not reduce the incidence of pure red cell aplasia in major ABO-mismatched transplants

Major ABO incompatibility in stem cell transplant recipients has been associated with pure red cell aplasia (PRCA). Reduction of incompatible isohaemagglutinin titres pre-transplant by various methods has been thought to reduce the incidence of PRCA. Our data suggest that pre-transplant reduction of incompatible isohaemagglutinin titres by donor group plasma infusion does not reduce the incidence of PRCA. We also failed to find any relationship between pre-transplant ABO isohaemagglutinin titre and the risk of developing PRCA

In-Sample Forecasting with Local Linear Survival Densities

In this paper, in-sample forecasting is defined as forecasting a structured density to sets where it is unobserved. The structured density consists of one-dimensional in-sample components that identify the density on such sets. We focus on the multiplicative density structure, which has recently been seen as the underlying structure of non-life insurance forecasts. In non-life insurance the in-sample area is defined as one triangle and the forecasting area as the triangle that 20 added to the first triangle produces a square. Recent approaches estimate two one-dimensional components by projecting an unstructured two-dimensional density estimator onto the space of multiplicatively separable functions. We show that time-reversal reduces the problem to two one-dimensional problems, where the one-dimensional data are left-truncated and a one-dimensional survival density estimator is needed. This paper then uses the local linear density smoother with 25 weighted cross-validated and do-validated bandwidth selectors. Full asymptotic theory is provided, with and without time reversal. Finite sample studies and an application to non-life insurance are included

Simulation of a Diesel Engine with Variable Geometry Turbocharger and Parametric Study of Variable Vane Position on Engine Performance

Modelling of a turbocharger is of interest to the engine designer as the work developed by the turbine can be used to drive a compressor coupled to it. This positively influences charge air density and engine power to weight ratio. Variable geometry turbocharger (VGT) additionally has a controllable nozzle ring which is normally electro-pneumatically actuated. This additional degree of freedom offers efficient matching of the effective turbine area for a wide range of engine mass flow rates. Closing of the nozzle ring (vanes tangential to rotor) result in more turbine work and deliver higher boost pressure but it also increases the back pressure on the engine induced by reduced turbine effective area. This adversely affects the net engine torque as the pumping work required increases. Hence, the optimum vane position for a given engine operating point is to be found through simulations or experimentation. A thermodynamic simulation model of a 2.2l 4 cylinder diesel engine was developed for investigation of different control strategies. Model features map based performance prediction of the VGT. Performance of the engine was simulated for steady state operation and validated with experimentation. The results of the parametric study of VGT’s vane position on the engine performance are discussed

Development of a Fuel Quantity based Engine Control Unit Software Architecture

   Conventionally diesel engines are controlled in open loop with maps based on engine speed and throttle position wherein fuel quantity is indirectly fixed using the rail pressure and injection duration maps with engine speed and throttle position as the independent variables which are measured by the respective sensors. In this work an engine control unit (ECU) software architecture where fuel quantity is directly specified in relation to the driver demand was implemented by modifying the control logic of a throttle position based framework. A desired fuel quantity for a given engine speed and throttle position was mapped from base line experiments on the reference engine. Injection durations and rail pressure required for this quantity was mapped on a fuel injector calibration test bench. The final calculation of injection duration in the new architecture is calculated using the fuel injector model. This enables determination of fuel quantity injected at any moment which directly indicates the torque produced by the engine at a given speed enabling smoke limited fuelling calculations and easing the implementation of control functions like all-speed governing

Development and Demonstration of Control Strategies for a Common Rail Direct Injection Armoured Fighting Vehicle Engine

The development of a controller which can be used for engines used in armoured fighting vehicles is discussed. This involved choosing a state of the art reference common rail automotive Diesel engine and setting-up of a transient engine testing facility. The dynamometer through special real-time software was controlled to vary the engine speed and throttle position. The reference engine was first tested with its stock ECU and its bounds of operation were identified. Several software modules were developed in-house in stages and evaluated on special test benches before being integrated and tested on the reference engine. Complete engine control software was thus developed in Simulink and flashed on to an open engine controller which was then interfaced with the engine. The developed control software includes strategies for closed loop control of fuel rail pressure, boost pressure, idle speed, coolant temperature based engine de-rating, control of fuel injection timing, duration and number of injections per cycle based on engine speed and driver input. The developed control algorithms also facilitated online calibration of engine maps and manual over-ride and control of engine parameters whenever required. The software was further tuned under transient conditions on the actual engine for close control of various parameters including rail pressure, idling speed and boost pressure. Finally, the developed control strategies were successfully demonstrated and validated on the reference engine being loaded on customised transient cycles on the transient engine testing facility with inputs based on military driving conditions. The developed controller can be scaled up for armoured fighting vehicle engines

Longitudinal Patterns of Mexican and Puerto Rican Children’s Asthma Controller Medication Adherence and Acute Healthcare Utilization

Rationale: Researchers tend to study Latinos as a single group but recent asthma research confirmed differences among Latino subgroups. Variations in controller medication adherence may be a factor in the observed health disparities between Mexican and Puerto Rican children. Adherence is not a stable phenomenon, however, there is a paucity of data on patterns of adherence, sociodemographic predictors of patterns, and variations in asthma-related acute healthcare utilization by adherence pattern among Latino sub-groups. Objectives: Identify patterns of inhaled corticosteroid medication adherence over twelve months among Mexican and Puerto Rican children with persistent asthma; examine sociodemographic predictors of adherence patterns by ethnicity; and investigate asthma-related acute healthcare utilization based on these patterns. Methods: We analyzed controller medication Doser data from Mexican and Puerto Rican children (n=123; ages 5-12 years) with persistent asthma who participated with their caregivers in a longitudinal, non-intervention study (Phoenix, AZ and Bronx, NY). Interview and medical record data were collected at enrollment, 3, 6, 9, and 12 months post-enrollment. Results: 47%-53% of children had poor adherence ( Conclusions: This study demonstrated that unique ethnicity within Latino populations may be associated with different risk levels for suboptimal controller medication adherence which may be a factor in the observed asthma health disparities between Mexican and Puerto Rican children. Increased understanding of and attention to children’s controller medication adherence patterns will provide evidence needed to identify children at highest risk for acute healthcare utilization and offer more intensive intervention using less-intensive approaches for those at low risk