Search results for "Econometric"
showing 10 items of 3780 documents
Sample size planning of two-arm superiority and noninferiority survival studies with discrete follow-up
2016
In clinical trials using lifetime as primary outcome variable, it is more the rule than the exception that even for patients who are failing in the course of the study, survival time does not become known exactly since follow-up takes place according to a restricted schedule with fixed, possibly long intervals between successive visits. In practice, the discreteness of the data obtained under such circumstances is plainly ignored both in data analysis and in sample size planning of survival time studies. As a framework for analyzing the impact of making no difference between continuous and discrete recording of failure times, we use a scenario in which the partially observed times are assig…
Some findings on zero-inflated and hurdle Poisson models for disease mapping
2018
Zero excess in the study of geographically referenced mortality data sets has been the focus of considerable attention in the literature, with zero-inflation being the most common procedure to handle this lack of fit. Although hurdle models have also been used in disease mapping studies, their use is more rare. We show in this paper that models using particular treatments of zero excesses are often required for achieving appropriate fits in regular mortality studies since, otherwise, geographical units with low expected counts are oversmoothed. However, as also shown, an indiscriminate treatment of zero excess may be unnecessary and has a problematic implementation. In this regard, we find …
Empirical study of the dependence of the results of multivariable flexible survival analyses on model selection strategy
2008
Flexible survival models, which avoid assumptions about hazards proportionality (PH) or linearity of continuous covariates effects, bring the issues of model selection to a new level of complexity. Each ‘candidate covariate’ requires inter-dependent decisions regarding (i) its inclusion in the model, and representation of its effects on the log hazard as (ii) either constant over time or time-dependent (TD) and, for continuous covariates, (iii) either loglinear or non-loglinear (NL). Moreover, ‘optimal’ decisions for one covariate depend on the decisions regarding others. Thus, some efficient model-building strategy is necessary. We carried out an empirical study of the impact of the model …
Comment on ‘Estimating average annual per cent change in trend analysis’ by Clegg LX, Hankey BF, Tiwari R, Feuer EJ, Edwards BK, Statistics in Medici…
2010
Trends in incidence or mortality rates over a specified time interval are usually described by the conventional annual per cent change (cAPC), under the assumption of a constant rate of change. When this assumption does not hold over the entire time interval, the trend may be characterized using the annual per cent changes from segmented analysis (sAPCs). This approach assumes that the change in rates is constant over each time partition defined by the transition points, but varies among different time partitions. Different groups (e.g. racial subgroups), however, may have different transition points and thus different time partitions over which they have constant rates of change, making co…
Bayesian modeling of the evolution of male height in 18th century Finland from incomplete data.
2012
Abstract Data on army recruits’ height are frequently available and can be used to analyze the economics and welfare of the population in different periods of history. However, such data are not a random sample from the whole population at the time of interest, but instead is skewed since the short men were less likely to be recruited. In statistical terms this means that the data are left-truncated. Although truncation is well-understood in statistics a further complication is that the truncation threshold is not known, may vary from time to time, and auxiliary information on the threshold is not at our disposal. The advantage of the fully Bayesian approach presented here is that both the …
Uncontrolled diabetes and health care utilisation:A bivariate latent Markov model approach
2018
Although uncontrolled diabetes (UD) or poor glycaemic control is a widespread condition with potentially life-threatening consequences, there is sparse evidence of its effects on health care utilisation. We jointly model the propensities to consume health care and UD by employing an innovative bivariate latent Markov model that allows for dynamic unobserved heterogeneity, movements between latent states and the endogeneity of UD. We estimate the effects of UD on primary and secondary health care consumption using a panel dataset of rich administrative records from Spain and measure UD using a biomarker. We find that, conditional on time-varying unobservables, UD does not have a statisticall…
Changes in performance and poling kinetics during cross-country sprint skiing competition using the double-poling technique
2013
In this study, changes in skiing performance and poling kinetics during a simulated cross-country sprint skiing competition were investigated. Twelve elite male cross-country skiers performed simulated sprint competition (4 x 1,150 m heat with 20 min recovery between the heats) using the double-poling technique. Vertical and horizontal pole forces and cycle characteristics were measured using a force plate system (20-m long) during the starting spurt, racing speed, and finishing spurt of each heat. Moreover, heat and 20-m phase velocities were determined. Vertical and horizontal pole impulses as well as mean cycle length were calculated. The velocities of heats decreased by 2.7 +/- 1.7% (p …
Is Food Self-Sufficiency Conducive to Long-Term Growth? An Assessment of Malthus (1803) on the International Corn Trade.
2017
In this article, we have reconstructed Malthus’s views on growth and international corn trade in the second edition of his An Essay on the Principle of Population (1803) and shown their theoretical consistency with Malthus’s food self-sufficiency policy proposal advanced in Grounds of an Opinion on the Policy of Restricting the Importation of Foreign Corn ([1815] 1986b), the protectionist pamphlet that elicited Ricardo’s vehement reaction in “Essay on Profits.” Malthus’s (1803) main thesis was that the contemporary British unbalanced growth pattern was not viable. In order to avoid premature stagnation, he thought that Great Britain should both follow a pattern of balanced growth and pursue…
Die Bedeutung von Emotionen für die wahrgenommene Fairness bei Preiserhöhungen
2011
Die wahrgenommene Fairness von Preisen hat sich als zentrales Konstrukt der Marketingforschung zur Analyse der Wirkung von Preiserhohungen etabliert. Ausgangspunkt der interdisziplinaren Preisfairnessforschung ist, dass Kunden ein Angebot nicht nur rational-okonomisch bewerten, sondern zusatzlich eine emotionale Komponente bei der Bewertung der Fairness eines Preises relevant ist. Dieser Beitrag bezieht sich daher auf die Analyse emotionaler Aspekte fur die Bildung des Fairnessurteils bei Preiserhohungen, wahrend bisherige Studien, mit wenigen Ausnahmen, auf die Untersuchung kognitiver Grosen abstellen. Die auf Basis der Equity-Theorie postulierte Relevanz von Emotionen fur das Fairnessurte…
Manager gender, entrepreneurial orientation and SMEs export and import propensities: evidence for Spanish businesses
2022
This paper investigates the role of manager gender in SMEs’ decisions to get involved in exporting and importing activities, using a sample of 1,405 Spanish SMEs. We borrow insights from international entrepreneurship theories and feminist theories to set testable hypotheses regarding how managerial gender and entrepreneurial orientation (proactiveness, risk-taking and innovativeness) may influence SMEs export and import propensities. Using a bivariate probit model and controlling for other managerial and business characteristics, results reveal that there are not significant disparities in exporting propensities between men- and women-run businesses. However, female-led SMEs show a lower i…