Target Quantities Research Articles

The use of decomposition in probability assessments of continuous variables

AbstractIn this study, decomposition is used as a tool for the assessment of continuous probability distributions. The goal of using decomposition is to obtain better calibrated probability distributions by expressing a variable as a known function of several component variables. Three target quantities were used in the study. Each was assessed holistically and using two different decompositions. Thus, each subject provided three distributions for each of the three target quantities. The recomposed assessments were compared to holistic assessments. The distributions obtained using decomposition were found to be much better calibrated than those obtained holistically. Two methods of aggregating distributions from multiple subjects were also examined. One involves aggregating (averaging) distributions before recomposing while the second method involves recomposing and then averaging distributions for the target variable. The second method was found to be slightly better, although both showed better calibration than was found in the individual assessments.

Methodik des produktionsintegrierten Umweltschutzes in der chemischen Industrie

AbstractMethods for Production‐Integrated Environmental Protection in the Chemical Industry. This article describes the integration of production‐integrated environmental protection in the chemical industry into strategic planning, research and development as an optimisation problem. A holistic approach is adopted to seek a compromise between contradictory economic, ecological, and other goals; these goals have to be prioritized subjectively. The ecological demands are quantified with the aid of technical factors, efficiency, and monetary factors. A methodology for decision making in production‐integrated environmental protection is demonstrated and discussed for a number of selected applications. It is based upon exact optimization with one or multiple target quantities, efficiency analysis, and quantitative models.

Pooling controls from different studies

This paper develops a method for estimating the odds ratio in a case-control study that 'borrows' strength from the controls in similar previous studies. We assume that the observations within each stratum in the current study are generated from a pair of independent binomial distributions. We assume that the observations on the controls, again within each stratum and from the previous studies, are independent binomial random variables. We use these controls to construct a prior distribution for the stratum specific log-odds for the controls in the current study which we then combine with the likelihood from the current study to arrive at the posterior distribution of the target quantities of interest, the adjusted or stratum specific log-odds ratios. We assume a diffuse prior distribution for the stratum specific log-odds ratio. A simulation study investigates the frequency or repeated sampling properties of the inference based upon the posterior distribution of the log-odds ratio so constructed.

Computer-aided formulation of experimental diets

A computer program has been designed to test-out random combinations of different numbers of food portions against set target quantities of nutrients required in experimental diets. The most acceptahle combination is selected and refined by random adjustments of the weight of each food component until a meal nutritionally closer to that required is achieved. Several complete meals are then incorporated into a diet by refining the weights of each meal until the complete diet matches the required one.

EMPIRICAL MEASURES OF CARBON TAXES

In this paper we compute the rates of taxes that would need to be imposed on carbon-based fuels to achieve the U.K. Government's targets for CO2 emission reductions, based on models of energy demand for the manufacturing, transport and domestic sectors. We explore the sensitivity of these tax rates to assumptions about rates of growth of output and prices, target quantities and dates, and show that the efficient policy of equal tax rates across the three sectors would reduce costs by 20 percent compared to a policy of equiproportionate reductions in emissions across the three sectors. Finally we consider the impact of trying to achieve a target for cumulative CO2 emissions over the period 1990-2010, but starting to implement policy at different dates. We show that the costs of delaying the implementation of policy would be considerable in the manufacturing sector, but much smaller in the other sectors. Copyright 1991 by Oxford University Press.

Sensitivity Analysis of Seasonal Adjustments: Empirical Case Studies

Abstract Three detailed case studies illustrating the seasonal analysis of economic time series are presented using component models for seasonal and nonseasonal behavior. Analyses are performed within a semi-Bayesian framework where inferences for target quantities of interest, such as seasonally adjusted values, are obtained as posterior distributions conditional on observed data and fitted parameter values. Such an approach is similar to previous model-based methods of seasonal analysis, but new models and algorithms are used and, more important, a sensitivity analysis is performed to determine the extent to which conclusions vary across a range of plausible fitted models. It is found that sensitivity to variation across plausible models is not unusual in practice. The logical conclusion of the investigation is that a fully Bayesian analysis is required that averages conditional posteriors over a posterior distribution for the model parameters. Such an analysis is necessarily sensitive to the choice of...

Sensitivity Analysis of Seasonal Adjustments: Empirical Case Studies

Abstract Three detailed case studies illustrating the seasonal analysis of economic time series are presented using component models for seasonal and nonseasonal behavior. Analyses are performed within a semi-Bayesian framework where inferences for target quantities of interest, such as seasonally adjusted values, are obtained as posterior distributions conditional on observed data and fitted parameter values. Such an approach is similar to previous model-based methods of seasonal analysis, but new models and algorithms are used and, more important, a sensitivity analysis is performed to determine the extent to which conclusions vary across a range of plausible fitted models. It is found that sensitivity to variation across plausible models is not unusual in practice. The logical conclusion of the investigation is that a fully Bayesian analysis is required that averages conditional posteriors over a posterior distribution for the model parameters. Such an analysis is necessarily sensitive to the choice of prior distribution. We believe that such dependencies on assumptions external to the data are inevitable in complex problems such as seasonal adjustment. The stochastic components of our nonseasonal and seasonal models are based on modified fractional Gaussian noise, as described in Carlin, Dempster, and Jonas (1985). The models allow for joint estimation of both fixed and random effects, a capability that is used to estimate the initial values of nonstationary components and is further illustrated in the data analysis by the use of trading-day adjustments. Our model structure is described in detail, but technical details of algorithms used to perform likelihood and conditional posterior calculations for fitted models are omitted in favor of the empirical case studies. The examples include some comparisons to the nonparametric X-11 method and to an autoregressive moving average modeling approach. One of the examples exhibits particularly striking differences between the model-based seasonal adjustments and those of X-11.

Determination of the parameters of the beam geometry in an electron beam welding installation

Abstract With the aid of statistical methods, mathematical relationships between given technological parameters and installation dimensions are found. Using the algorithms obtained, the plant settings are calculated from the target quantities using a control computer (K1520) as required and for any value within the range of settings, and these are set in the EB installation.

ChemInform Abstract: Packings and Stationary Phases in Preparative Column Liquid Chromatography

Abstract Although the theoretical treatment of chromatographic processes on a preparative scale provides guidelines to the extent to which packing and stationary phase properties affect the target quantities such as sample input, throughput and resolution times sample input, a series of additional criteria were established to judge the quality of a packing in preparative column liquid chromatography. These include bed stability and flow resistance, chemical resistance and purity, solute accessibility, mass and biological recovery, fouling, regeneration and cost. Applying these criteria, the relative importance of physical and chemical structure parameters of packings and stationary phases was assessed. Commercial packings with mean particle diameters d p > 20 μm were listed for adsorption, size exclusion, ion-exchange and affinity chromatography. An analysis of the characteristic features of phase systems showed that adsorption media offer a high selectivity combined with adequate loadability, whereas ion exchangers and affinity media were best suited for biospecific solutes, particularly biopolymers, which can be attributed to their high selectivity and load ability.

Problems in data compilation

Concepts involved in the estimation of target quantities and other adjustment parameters are critically discussd. We point out that one can find more accurate precepts for the reduction of data by utilizing all available constraints on all available data in the derivation of the reduction precepts. We introduce a measure for the efficiencyof a set of adjustment parameters such that adjustments carried out using different precepts can be objectively compared. Finally, having applied our suggestions to a specific problem, we show that we have obtained estimates of a set of target quantities (in our case, star positions and proper motions) which have smaller formal errors than estimates of the same target quantities derived from the same input material but following traditional procedures.

SOME STATISTICAL ISSUES IN THE ESTIMATION OF A SIMPLE COST‐VOLUME‐PROFIT MODEL*

ABSTRACTThis paper presents point and interval estimators of both long‐run and single‐period target quantities in a simple cost‐volume‐profit (C‐V‐P) model. This model is a stochastic version of the “accountant's break‐even chart” where the major component is a semivariable cost function. Although these features suggest obvious possibilities for practical application, a major purpose of this paper is to examine the statistical properties of target quantity estimators in C‐V‐P analysis. It is shown that point estimators of target quantity are biased and possess no moments of positive order, but are consistent. These properties are also shared by previous break‐even models, even when all parameters are assumed known with certainty. After a test for positive variable margins, Fieller's [6] method is used to obtain interval estimators of relevant target quantities. This procedure therefore minimizes possible ambiguities in stochastic break‐even analysis (noted by Ekern [3]).

On Systems of Standards

Rigorous formulations closely following current practice, are proposed for the absolute and the relative estimation of certain target quantities. A system of standards is defined as a set of estimates that has certain properties. This is followed by a discussion of the meaning of “reducing estimates to a specified system“ and certain procedures are suggested for making this process less ambiguous. It is finally shown that relative estimates can be employed for replacing a system which is based on absolute measurements alone by another, more accurate system.

SOME TESTS OF BINOMIAL PROBABILITY ASSESSMENTS

AbstractA replication of the Alpert‐Raiffa probability assessment experiment is used to motivate the development of several tests for evaluating assessors. The tests permit an evaluation of an assessor's accuracy in estimating target quantities and in estimating his own uncertainty as well.Assumption of normal subjective distributions permits the determination of subjective variances. Data from trial assessments are employed to test models which assert that assessed quantities are equal to subjectively assessed error variances. Several tests of the latter type are compared using data from individual, as well as pooled, assessors.

Detection of prompt deexcitation γ-rays following bremsstrahlung-induced reactions with the aid of large volume Ge(Li) detectors

An experimental arrangement at the bremsstrahlung beam of a 65 MeV electron linac has been optimized with regard to the detection of prompt deexcitation γ-rays from small target quantities by Ge(Li) detectors. The 100 cm 3 Ge(Li) diodes have been calibrated by means of radioactive sources and radiative proton capture reactions. The influence of counting rate effects and background radiation during the bremsstrahlung burst are discussed. Deexcitation photon spectra from 28Si(γ,γ′), 25Mg(γ,χγ′) and 31P(γ,χγ′) reactions are presented.

Thermal neutron capture gammas measured with Ge(Li)-spectrometers and internal reactor targets

An experimental arrangement for the study of thermal neutron capture gammas from reactions with low cross sections or where use is made of small amounts of separated isotopes is described. In this arrangement a through evacuated reactor channel and Ge(Li)-spectrometers for gamma detection are used. For the measurement of capture gammas above the pair production threshold a three crystal pair spectrometer employing a Ge(Li)-crystal surrounded by a bisected NaI-annulus is used. For the measurement of the low energy part of (n, γ)-spectra the same annulus is used in the anticoincidence mode. The efficiency of the anticoincidence mantle for detecting backscattered quanta from the Ge(Li)-crystal is increased by adding a 5″ dia. × 4″ long NaI-crystal with a through axial hole to the anticoincidence assembly. The functioning of the spectrometers is illustrated with capture gammas from the A(n, γ)- and Fe(n, γ)-reactions. The efficiency of the spectrometers and the background conditions are discussed and related to the minimum target quantities required.