Loading

Error: Cannot Load Popup Box

Hit List

Title:

Stochastic frontier models with dependent error components

Description:

of the stochastic frontier model are assumed to be independent random variables. By employing the copula approach to statistical modelling, the joint behaviour of U and V can be parametrized thereby allowing the data the opportunity to determine the adequacy of the independence assumption. In this context, three examples of the copula approach a...

of the stochastic frontier model are assumed to be independent random variables. By employing the copula approach to statistical modelling, the joint behaviour of U and V can be parametrized thereby allowing the data the opportunity to determine the adequacy of the independence assumption. In this context, three examples of the copula approach are given: the first is algebraic (the Logistic-Exponential stochastic frontier model with margins bound by the Farlie--Gumbel--Morgenstern copula), the second uses a cross-section of cost data sampled from the US electrical power industry and the third constructs a model for panel data that is then used to conduct a Monte Carlo exercise in which estimator bias is examined when the dependence structure is incorrectly ignored. Copyright Royal Economic Society 2007 Minimize

Document Type:

article

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Modelling sample selection using Archimedean copulas

Description:

By a theorem due to Sklar, a multivariate distribution can be represented in terms of its underlying margins by binding them together using a copula function. By exploiting this representation, the "copula approach" to modelling proceeds by specifying distributions for each margin and a copula function. In this paper, a number of families of cop...

By a theorem due to Sklar, a multivariate distribution can be represented in terms of its underlying margins by binding them together using a copula function. By exploiting this representation, the "copula approach" to modelling proceeds by specifying distributions for each margin and a copula function. In this paper, a number of families of copula functions are given, with attention focusing on those that fall within the Archimedean class. Members of this class of copulas are shown to be rich in various distributional attributes that are desired when modelling. The paper then proceeds by applying the copula approach to construct models for data that may suffer from selectivity bias. The models examined are the self-selection model, the switching regime model and the double-selection model. It is shown that when models are constructed using copulas from the Archimedean class, the resulting expressions for the log-likelihood and score facilitate maximum likelihood estimation. The literature on selectivity modelling is almost exclusively based on multivariate normal specifications. The copula approach permits selection modelling based on multivariate non-normality. Examples of self-selection models for labour supply and for duration of hospitalization illustrate the application of the copula approach to modelling. Copyright Royal Economic Society, 2003 Minimize

Document Type:

article

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Stochastic Frontier Models With Correlated Error Components

Description:

In the productivity modelling literature, the disturbances U (representing technical inefficiency) and V (representing noise) of the composite error W=V-U of the stochastic frontier model are assumed to be independent random variables. By employing the copula approach to statistical modelling, the joint behaviour of U and V can be parameterised ...

In the productivity modelling literature, the disturbances U (representing technical inefficiency) and V (representing noise) of the composite error W=V-U of the stochastic frontier model are assumed to be independent random variables. By employing the copula approach to statistical modelling, the joint behaviour of U and V can be parameterised thereby allowing the data the opportunity to determine the adequacy of the independence assumption. In this context, three examples of the copula approach are given: the first is algebraic (the Logistic-Exponential stochastic frontier model with margins bound by the Fairlie-Gumbel-Morgenstern copula) and the second and third are empirically oriented, using data sets well-known in productivity analysis. Analysed are a cross-section of cost data sampled from the US electrical power industry, and an unbalanced panel of data sampled from the US airline industry ; Stochastic Frontier model; Copula; Copula approach; Sklar's theorem; Families of copulas; Spearman's rho. Minimize

Document Type:

preprint

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Using Copulas to Model Switching Regimes with an Application to Child Labour

Description:

The copula approach to econometric modelling involves the specification of the separate components of the joint distribution of the random variables of interest: models built for each margin are bound together using a copula function. In this paper, the copula approach is used to construct models for switching regimes. The construct is illustrat...

The copula approach to econometric modelling involves the specification of the separate components of the joint distribution of the random variables of interest: models built for each margin are bound together using a copula function. In this paper, the copula approach is used to construct models for switching regimes. The construct is illustrated by fitting a wage earnings model for child workers in the early 1900s, with regimes governed according to literacy. The results improve on earlier modelling efforts by Poirier and Tobias (2003), finding that a child worker may on average expect a reduction in earnings from being literate. Copyright 2005 The Economic Society Of Australia. Minimize

Document Type:

article

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Infant mortality and child nutrition in Bangladesh

Author:

Description:

The excess female infant mortality observed in South Asia has typically been attributed to gender discrimination in the intra-household allocation of food and medical care. However, studies on child nutrition find no evidence of gender differences. A natural explanation could be that in environments of high infant mortality of females, the survi...

The excess female infant mortality observed in South Asia has typically been attributed to gender discrimination in the intra-household allocation of food and medical care. However, studies on child nutrition find no evidence of gender differences. A natural explanation could be that in environments of high infant mortality of females, the surviving children are healthier, so that child nutrition cannot be studied independently of mortality. In this paper, we use data from the 2004 Bangladesh Demographic Health Survey to investigate if there are any gender differences in survival probabilities and whether this leads to differences in child nutrition. We argue the importance of establishing whether or not there exists a dependence relationship between the two random variables - infant mortality and child nutrition - and in order to detect this we employ a copula approach to model specification. The results suggest, for example, that while male children have a significantly lower likelihood of surviving their first year relative to female children, should they survive they have significantly better height-for-age Z-scores. From a policy perspective, household wealth and public health interventions such as vaccinations are found to be important predictors of better nutritional outcomes. Copyright © 2008 John Wiley & Sons, Ltd. Minimize

Document Type:

article

Content Provider:

My Lists:

My Tags:

Notes:

Title:

2

Description:

Abstract: By a theorem due to Sklar, a multivariate distribution can be represented in terms of its underlying margins by binding them together using a copula function. By exploiting this representation, the “copula approach ” to modelling proceeds by specifying distributions for each margin, and a copula function. In this article, a number of c...

Abstract: By a theorem due to Sklar, a multivariate distribution can be represented in terms of its underlying margins by binding them together using a copula function. By exploiting this representation, the “copula approach ” to modelling proceeds by specifying distributions for each margin, and a copula function. In this article, a number of copula functions are given, with attention focusing on members of the Archimedean class. This class of copulas is shown to be su¢ciently rich in regard to permitting various distributional attributes as may be desired when modelling. The article then proceeds by applying the copula approach to construct models for data that may su¤er from sample selection. When Archimedean copulas are used, expressions are obtained for the log-likelihood and score that facilitate maximum likelihood estimation. The literature on selection models is almost exclusively based on multivariate normal speci…cations. Consequently, the extension to multivariate non-normality made possible by adopting a copula approach, contributes a new source of modelling technique to the practitioner’s toolkit. Examples of self-selection models for labour supply, and for the duration of hospitalisation, illustrate the application of the copula approach to modelling. Minimize

Contributors:

The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2011-10-28

Source:

http://www.business.qut.edu.au/esam02/program/papers/Smith_Murray.pdf

http://www.business.qut.edu.au/esam02/program/papers/Smith_Murray.pdf Minimize

Document Type:

text

Language:

en

Subjects:

Selectivity ; Self-selection model ; Sklar’s theorem ; Copula ; Archimedean copula

Selectivity ; Self-selection model ; Sklar’s theorem ; Copula ; Archimedean copula Minimize

DDC:

310 Collections of general statistics *(computed)*

Rights:

Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Adherence to inhaled corticosteroids by asthmatic patients: measurement and modelling

Author:

Description:

Background Poor adherence to inhaled corticosteroids (ICS) is known as the main cause for therapeutic failure in asthma treatment and associated morbidity. To improve adherence, targetted and effective interventions need to be developed ideally based on using longitudinal follow-up of a large study cohort to establish patterns and influences on ...

Background Poor adherence to inhaled corticosteroids (ICS) is known as the main cause for therapeutic failure in asthma treatment and associated morbidity. To improve adherence, targetted and effective interventions need to be developed ideally based on using longitudinal follow-up of a large study cohort to establish patterns and influences on adherence. Objective To develop an annual measure of asthma patients’ adherence to ICS using primary care prescribing data over consecutive annual intervals, and to statistically model ICS adherence controlling for a range of patient factors. Setting A retrospective cohort study between 1997 and 2010 using United Kingdom general practice prescribing data on asthma patients aged between 12 and 65 years, without a diagnosis of chronic obstructive pulmonary disease. Method Patient’s ICS prescriptions are used to calculate the ‘number of days prescribed during calendar year’ divided by ‘number of days in the interval’ to form an annual prescription possession ratio (PPR) for each patient. Several definitions of PPR are considered and compared when calculating numerator and denominator. Adherence, measured by the preferred PPR, is then modelled to estimate the effect of asthma exacerbation, severity, control and other patient factors on adherence. Main outcome measure PPR, being a proxy measure for adherence. Results Annual PPR by all strategies gave a similar frequency profile. ICS were either over- or under-prescribed for over half of the follow-up time. Adherence was lower in younger patients, those newer to the study timeframe, those with less severe asthma, those with good control, with lower previous adherence, and who had not previously experienced an exacerbation. Conclusion The chosen PPR simulated clinical use of ICS most closely; including overlapping days, excess days passed to the next interval, considering gaps in the denominator, with censoring at 100 %. The PPR is a useful measure for signalling or measuring adherence changes over time. The modelling results identified many characteristics which would indicate which asthma patients and at what points in their treatment cycle they would be at increased risk of low adherence. Minimize

Publisher:

Springer Netherlands

Year of Publication:

2014-02-01

Source:

International Journal of Clinical Pharmacy, 2014-02-01, Volume 36, pp 112-119

International Journal of Clinical Pharmacy, 2014-02-01, Volume 36, pp 112-119 Minimize

Document Type:

Research Article

Language:

En

Subjects:

Adherence ; Asthma ; Exacerbation ; Panel data ; Prescription possession ratio

Adherence ; Asthma ; Exacerbation ; Panel data ; Prescription possession ratio Minimize

Rights:

Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Minimize

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Mathematical Statistics with Mathematica, by Colin

Author:

Description:

This book is an accompaniment to the computer software package mathStatica (which runs as an add-on to Mathematica). The book comes with two CD-ROMS: mathStatica, and a 30-day trial version of Mathematica 4.1. The mathStatica CD-ROM includes an applications pack for doing mathematical statistics, custom Mathematica palettes and an electronic ver...

This book is an accompaniment to the computer software package mathStatica (which runs as an add-on to Mathematica). The book comes with two CD-ROMS: mathStatica, and a 30-day trial version of Mathematica 4.1. The mathStatica CD-ROM includes an applications pack for doing mathematical statistics, custom Mathematica palettes and an electronic version of the book that is identical to the printed text, but can be used interactively to generate animations of some of the book’s figures (e.g. as a parameter is varied). (I found this last feature particularly valuable.) MathStatica has statistical operators for determining expectations (and hence characteristic functions, for example) and probabilities, for finding the distributions Minimize

Contributors:

The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2013-10-25

Source:

http://www.mathstatica.com/reviews/Quine.pdf

http://www.mathstatica.com/reviews/Quine.pdf Minimize

Document Type:

text

Language:

en

Rights:

Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Symbolic Maximum Likelihood Estimation with Mathematic

Description:

Summary. Mathematica is a symbolic programming language that empowers the user to undertake complicated algebraic tasks. One such task is the derivation of maximum likelihood estimators, demonstrably an important topic in statistics at both the research and the expository level. In this paper, a Mathematica package is provided that contains a fu...

Summary. Mathematica is a symbolic programming language that empowers the user to undertake complicated algebraic tasks. One such task is the derivation of maximum likelihood estimators, demonstrably an important topic in statistics at both the research and the expository level. In this paper, a Mathematica package is provided that contains a function entitled SuperLog. This function utilizes pattern-matching code that enhances Mathematica's ability to simplify expressions involving the natural logarithm of a product of algebraic terms. This enhancement to Mathematica's functionality can be of particular bene®t for maximum likelihood estimation. Minimize

Contributors:

The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2010-09-14

Source:

http://www.tri.org.au/RoseSmithD.pdf

http://www.tri.org.au/RoseSmithD.pdf Minimize

Document Type:

text

Language:

en

Subjects:

Computer algebra systems ; Estimate ; Estimator ; Mathematica ; Symbolic maximum likelihood ; Teaching

Computer algebra systems ; Estimate ; Estimator ; Mathematica ; Symbolic maximum likelihood ; Teaching Minimize

Rights:

Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Title:

Symbolic Maximum Likelihood Estimation with Mathematica

Description:

this paper, a Mathematica package is provided that contains a function entitled SuperLog. This function utilises pattern-matching code that enhances Mathematica's ability to simplify expressions involving the natural logarithm of a product of algebraic terms. This enhancement to Mathematica's functionality can be of particular benefit for maximu...

this paper, a Mathematica package is provided that contains a function entitled SuperLog. This function utilises pattern-matching code that enhances Mathematica's ability to simplify expressions involving the natural logarithm of a product of algebraic terms. This enhancement to Mathematica's functionality can be of particular benefit for maximum likelihood estimation. Keywords: Computer algebra systems; Estimate; Estimator; Mathematica; Minimize

Contributors:

The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2009-04-13

Source:

ftp://ftp.stat.uni-muenchen.de/pub/sfb386/paper141.ps.Z

ftp://ftp.stat.uni-muenchen.de/pub/sfb386/paper141.ps.Z Minimize

Document Type:

text

Language:

en

Subjects:

Computer algebra systems ; Estimate ; Estimator ; Mathematica ; Symbolic maximum likelihood ; Teaching

Computer algebra systems ; Estimate ; Estimator ; Mathematica ; Symbolic maximum likelihood ; Teaching Minimize

Rights:

Metadata may be used without restrictions as long as the oai identifier remains attached to it.

URL:

Content Provider:

My Lists:

My Tags:

Notes:

Currently in BASE: 70,931,017 Documents of 3,410 Content Sources

http://www.base-search.net