Predictive Regressions

2019 ◽  
Author(s):  
Jesús Gonzalo ◽  
Jean-Yves Pitarakis
Keyword(s):  
Model Parameters ◽  
Specific Behavior ◽  
Standard Methods ◽  
Financial Variables ◽  
Predictive Regressions ◽  
Frequent Use ◽  
Linear Setting

Predictive regressions are a widely used econometric environment for assessing the predictability of economic and financial variables using past values of one or more predictors. The nature of the applications considered by practitioners often involve the use of predictors that have highly persistent, smoothly varying dynamics as opposed to the much noisier nature of the variable being predicted. This imbalance tends to affect the accuracy of the estimates of the model parameters and the validity of inferences about them when one uses standard methods that do not explicitly recognize this and related complications. A growing literature aimed at introducing novel techniques specifically designed to produce accurate inferences in such environments ensued. The frequent use of these predictive regressions in applied work has also led practitioners to question the validity of viewing predictability within a linear setting that ignores the possibility that predictability may occasionally be switched off. This in turn has generated a new stream of research aiming at introducing regime-specific behavior within predictive regressions in order to explicitly capture phenomena such as episodic predictability.

scholarly journals Choice between Rent and Mortgage: Evaluating the Net Present Value of Home Ownership

2019 ◽  
Vol 11 (4) ◽  
pp. 7-18
Author(s):  
O. I. Ivanov ◽  
M. M.S. Naimi
Keyword(s):  
Real Estate ◽  
Net Present Value ◽  
Home Ownership ◽  
Housing Prices ◽  
Mortgage Lending ◽  
Mortgage Market ◽  
Model Parameters ◽  
Macroeconomic Conditions ◽  
Financial Variables ◽  
Mortgage Interest

The article considers the problem of choosing between the ownership of residential real estate and its rental as a solution to the investment problem. The purpose of the article is to formalize this task using only financial variables (without explicitly including non-monetary preferences) and testing it on real Russian data on real estate and mortgage lending markets. The results can be used: a) at the house-hold level, which usually poorly take into account the financial side of the decision; b) at the level of macroeconomic policy to predict the dynamics of the mortgage market. We identified the following key model parameters: the expected rate of growth in housing and rental prices, mortgage interest, and the planned period of real estate ownership. The model demonstrates that for an average of Moscow or Russian housing with enough period of ownership, the purchase is generally more profitable in the cur-rent macroeconomic conditions. However, if the forecast for the dynamics of changes in housing prices worsens, when the nominal price increase is 5-8% lower than the discount rate, the answer may change in favor of renting. This is especially true in connection with the negative dynamics of real prices in the Russian housing market.  

scholarly journals Problems of Modelling Toxic Compounds Emitted by a Marine Internal Combustion Engine in Unsteady States

2015 ◽  
Vol 21 (4) ◽  
pp. 57-65 ◽  
Author(s):  
Jacek Rudnicki ◽  
Ryszard Zadrąg
Keyword(s):  
Combustion Engine ◽  
Neural Model ◽  
Multiple Regression Model ◽  
Diagnostic Tools ◽  
Model Parameters ◽  
Single Output ◽  
Frequent Use ◽  
Measurement Results ◽  
Sample Application ◽  
Analytical Tools

Abstract Contemporary engine tests are performed based on the theory of experiment. The available versions of programmes used for analysing experimental data make frequent use of the multiple regression model, which enables examining effects and interactions between input model parameters and a single output variable. The use of multi-equation models provides more freedom in analysing the measured results, as those models enable simultaneous analysis of effects and interactions between many output variables. They can also be used as a tool in preparing experimental material for other advanced diagnostic tools, such as the models making use of neural networks which, when properly prepared, enable also analysing measurement results recorded during dynamic processes. The article presents advantages of the use of the abovementioned analytical tools and a sample application of the neural model developed based on the results of examination carried out on the engine research rig.

scholarly journals Estimating the frequency of indolent breast cancer in screening trials

2018 ◽  
Vol 28 (4) ◽  
pp. 1261-1271
Author(s):  
Yu Shen ◽  
Wenli Dong ◽  
Roman Gulati ◽  
Marc D Ryser ◽  
Ruth Etzioni
Keyword(s):  
Breast Cancer ◽  
Cancer Screening ◽  
Screening Test ◽  
Accurate Estimation ◽  
Model Parameters ◽  
Interval Cancers ◽  
Standard Methods ◽  
Test Sensitivity ◽  
Satisfactory Performance ◽  
Screening Trials

Cancer screening can detect cancer that would not have been detected in a patient’s lifetime without screening. Standard methods for analyzing screening data do not explicitly account for the possibility that a fraction of tumors may remain latent indefinitely. We extend these methods by representing cancers as a mixture of those that progress to symptoms (progressive) and those that remain latent (indolent). Given sensitivity of the screening test, we derive likelihood expressions to simultaneously estimate (1) the rate of onset of preclinical cancer, (2) the average preclinical duration of progressive cancers, and (3) the fraction of preclinical cancers that are indolent. Simulations demonstrate satisfactory performance of the estimation approach to identify model parameters subject to precise specifications of input parameters and adequate numbers of interval cancers. In application to four breast cancer screening trials, the estimated indolent fraction among preclinical cancers varies between 2% and 35% when assuming 80% test sensitivity and varying specifications for the earliest time that participants could plausibly have developed cancer. We conclude that standard methods for analyzing screening data can be extended to allow some indolent cancers, but accurate estimation depends on correctly specifying key inputs that may be difficult to determine precisely in practice.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

Ultrastructural Localization of Phycocyanin in the Acidophilic, Thermophilic Alga, Cyanidium Caldarium

1973 ◽  
Vol 31 ◽  
pp. 462-463
Author(s):  
M. R. Edwards ◽  
J. D. Mainwaring
Keyword(s):  
Yellowstone National Park ◽  
National Park ◽  
Ultrastructural Localization ◽  
Review Of Literature ◽  
Cyanidium Caldarium ◽  
Taxonomic Rank ◽  
Thin Sections ◽  
Standard Methods ◽  
Laboratory Cultures

Although the general ultrastructure of Cyanidium caldarium, an acidophilic, thermophilic alga of questionable taxonomic rank, has been extensively studied (see review of literature in reference 1), some peculiar ultrastructural features of the chloroplast of this alga have not been noted by other investigators.Cells were collected and prepared for thin sections at the Yellowstone National Park and were also grown in laboratory cultures (45-52°C; pH 2-5). Fixation (glutaraldehyde-osmium), dehydration (ethanol), and embedding (Epon 812) were accomplished by standard methods. Replicas of frozenfracture d- etched cells were obtained in a Balzers apparatus. In addition, cells were examined after disruption in a French Press.

A Device for Magnification Measurement

1972 ◽  
Vol 30 ◽  
pp. 622-623
Author(s):  
J.A. Eades ◽  
A. van Dun
Keyword(s):  
Electron Microscope ◽  
Small Displacement ◽  
Private Communication ◽  
Piezoelectric Crystal ◽  
Double Exposure ◽  
Standard Methods ◽  
Elegant Method ◽  
The Right ◽  
Piezo Electric

The measurement of magnification in the electron microscope is always troublesome especially when a goniometer stage is in use, since there can be wide variations from calibrated values. One elegant method (L.M.Brown, private communication) of avoiding the difficulties of standard methods would be to fit a device which displaces the specimen a small but known distance and recording the displacement by a double exposure. Such a device would obviate the need for changing the specimen and guarantee that the magnification was measured under precisely the conditions used.Such a small displacement could be produced by any suitable transducer mounted in one of the specimen translation mechanisms. In the present case a piezoelectric crystal was used. Modern synthetic piezo electric ceramics readily give reproducible displacements in the right range for quite modest voltages (for example: Joyce and Wilson, 1969).

Convergent-beam thickness determination: The advantages of digital imaging

1994 ◽  
Vol 52 ◽  
pp. 420-421
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Intensity Variation ◽  
Convergent Beam Electron Diffraction ◽  
Digital Data ◽  
Thickness Determination ◽  
Frequent Use ◽  
Automated Processing ◽  
Beam Thickness ◽  
Convergent Beam ◽  
Remarkable Agreement

Convergent-beam electron diffraction (CBED) patterns contain an immense amount of information relating to the structure of the material from which they are obtained. The analysis of these patterns has progressed to the point that under appropriate, well specified conditions, the intensity variation within the CBED discs may be understood in a quantitative sense. Rossouw et al for example, have produced numerical simulations of zone-axis CBED patterns which show remarkable agreement with experimental patterns. Spence and co-workers have obtained the structure factor parameters for lowindex reflections using the intensity variation in 2-beam CBED patterns. Both of these examples involve the use of digital data. Perhaps the most frequent use for quantitative CBED analysis is the thickness determination described by Kelly et al. This analysis has been implemented in a variety of different ways; from real-time, in-situ analysis using the microscope controls, to measurements of photographic prints with a ruler, to automated processing of digitally acquired images. The potential advantages of this latter process will be presented.

Instrumental and Ideological Union Commitment: Longitudinal Assessment of Construct Validity

2001 ◽  
Vol 17 (2) ◽  
pp. 98-111 ◽  
Author(s):  
Anders Sjöberg ◽  
Magnus Sverke
Keyword(s):  
Construct Validity ◽  
Temporal Stability ◽  
Strong Support ◽  
Internal Consistency Reliability ◽  
Measurement Model ◽  
Two Dimensions ◽  
Model Parameters ◽  
Longitudinal Assessment ◽  
Union Commitment ◽  
Union Participation

Summary: Previous research has identified instrumentality and ideology as important aspects of member attachment to labor unions. The present study evaluated the construct validity of a scale designed to reflect the two dimensions of instrumental and ideological union commitment using a sample of 1170 Swedish blue-collar union members. Longitudinal data were used to test seven propositions referring to the dimensionality, internal consistency reliability, and temporal stability of the scale as well as postulated group differences in union participation to which the scale should be sensitive. Support for the hypothesized factor structure of the scale and for adequate reliabilities of the dimensions was obtained and was also replicated 18 months later. Tests for equality of measurement model parameters and test-retest correlations indicated support for the temporal stability of the scale. In addition, the results were consistent with most of the predicted differences between groups characterized by different patterns of change/stability in union participation status. The study provides strong support for the construct validity of the scale and indicates that it can be used in future theory testing on instrumental and ideological union commitment.

Is thyroid surgery performed too often in Germany?

2015 ◽  
Vol 54 (03) ◽  
pp. 101-105 ◽  
Author(s):  
F. A. Verburg
Keyword(s):  
Surgical Procedures ◽  
Thyroid Surgery ◽  
Needle Biopsy ◽  
Fine Needle Biopsy ◽  
Contributing Factors ◽  
Fine Needle ◽  
Diagnostic Measures ◽  
Frequent Use ◽  
Preoperative Diagnostic ◽  
The Usa

SummaryThyroid surgery is one of the more common surgical procedures in Germany. This is in contrast with the situation in some other countries, where this procedure is performed comparatively rarely. In this paper the number of thyroid surgeries in Germany is compared with other western countries (Netherlands, USA, England). In contrast to e. g. the USA and England the number of thyroid surgeries in Germany is declining, however with approximately 109/100 000/year in 2012 is still elevated (Netherlands: 16/100 000/year, USA: at least 42/100 000/year, England: at least 27/100 000/year).Possible contributing factors to this higher number of thyroid surgeries in Germany are explored. These factors include iodine deficiency, the frequent use of advanced diagnostics such as ultrasound, insufficient use of preoperative diagnostic measures such as fine needle biopsy and the practice of “defensive medicine”. How much each of these factors contributes is however unclear.

The Repair and Healing of Two Traumatic Ilial Body Fractures Adjacent to Cemented Total Hip Acetabular Components

1992 ◽  
Vol 05 (02) ◽  
pp. 85-89
Author(s):  
P. K. Shires ◽  
T. L. Dew
Keyword(s):  
Internal Fixation ◽  
Cancellous Bone ◽  
Surgical Techniques ◽  
Autogenous Bone ◽  
Cancellous Bone Graft ◽  
Standard Methods ◽  
Intravenous Antibiotics ◽  
Prophylactic Use ◽  
Acetabular Components ◽  
Autogenous Bone Grafts

SummaryThis report has documented the repair and healing of two ilial fractures in dogs which were compounded by the presence of a cemented acetabular prosthesis. While specific recommendations can not be made from such a small number of cases, the information presented herein suggests that such fractures will heal without complication if aseptic surgical techniques and standard methods of internal fixation are employed. The authors strongly recommend the prophylactic use of intravenous antibiotics and the placement of cancellous bone graft when the repair of such fractures is attempted.Two traumatic ilial fractures involving the cement/bone interface of acetabular prostheses were repaired using lag screws, cerclage wires, and autogenous bone grafts. The fractures healed and ambulatory function was regained.

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