Comparing Johnson’s SBB, Weibull and Logit-Logistic bivariate distributions for modeling tree diameters and heights using copulas

Aim of study: In this study we compare the accuracy of three bivariate distributions: Johnson’s SBB, Weibull-2P and LL-2P functions for characterizing the joint distribution of tree diameters and heights.Area of study: North-West of Spain.Material and methods: Diameter and height measurements of 128 plots of pure and even-aged Tasmanian blue gum (Eucalyptus globulus Labill.) stands located in the North-west of Spain were considered in the present study. The SBB bivariate distribution was obtained from SB marginal distributions using a Normal Copula based on a four-parameter logistic transformation. The Plackett Copula was used to obtain the bivariate models from the Weibull and Logit-logistic univariate marginal distributions. The negative logarithm of the maximum likelihood function was used to compare the results and the Wilcoxon signed-rank test was used to compare the related samples of these logarithms calculated for each sample plot and each distribution.Main results: The best results were obtained by using the Plackett copula and the best marginal distribution was the Logit-logistic.Research highlights: The copulas used in this study have shown a good performance for modeling the joint distribution of tree diameters and heights. They could be easily extended for modelling multivariate distributions involving other tree variables, such as tree volume or biomass.

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Mass transportation problems with capacity constraints

Journal of Applied Probability ◽

10.1239/jap/1032374463 ◽

1999 ◽

Vol 36 (2) ◽

pp. 433-445 ◽

Cited By ~ 3

Author(s):

S. T. Rachev ◽

I. Olkin

Keyword(s):

Joint Distribution ◽

Bivariate Distribution ◽

Capacity Constraints ◽

Distribution Functions ◽

Mass Transportation ◽

Marginal Distributions ◽

Transportation Problems ◽

The Family ◽

Additional Capacity ◽

Additional Constraints

We exhibit solutions of Monge–Kantorovich mass transportation problems with constraints on the support of the feasible transportation plans and additional capacity restrictions. The Hoeffding–Fréchet inequalities are extended for bivariate distribution functions having fixed marginal distributions and satisfying additional constraints. Sharp bounds for different probabilistic functionals (e.g. Lp-distances, covariances, etc.) are given when the family of joint distribution functions has prescribed marginal distributions, satisfies restrictions on the support, and is bounded from above, or below, by other distributions.

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Comparing Forecast Skill

Monthly Weather Review ◽

10.1175/mwr-d-14-00045.1 ◽

2014 ◽

Vol 142 (12) ◽

pp. 4658-4678 ◽

Cited By ~ 35

Author(s):

Timothy DelSole ◽

Michael K. Tippett

Keyword(s):

Climate Model ◽

Permutation Test ◽

Statistical Significance ◽

Forecast Skill ◽

Sign Test ◽

Rank Test ◽

Basic Question ◽

Seasonal Forecasts ◽

The North ◽

Signed Rank Test

Abstract A basic question in forecasting is whether one prediction system is more skillful than another. Some commonly used statistical significance tests cannot answer this question correctly if the skills are computed on a common period or using a common set of observations, because these tests do not account for correlations between sample skill estimates. Furthermore, the results of these tests are biased toward indicating no difference in skill, a fact that has important consequences for forecast improvement. This paper shows that the magnitude of bias is characterized by a few parameters such as sample size and correlation between forecasts and their errors, which, surprisingly, can be estimated from data. The bias is substantial for typical seasonal forecasts, implying that familiar tests may wrongly judge that differences in seasonal forecast skill are insignificant. Four tests that are appropriate for assessing differences in skill over a common period are reviewed. These tests are based on the sign test, the Wilcoxon signed-rank test, the Morgan–Granger–Newbold test, and a permutation test. These techniques are applied to ENSO hindcasts from the North American Multimodel Ensemble and reveal that the Climate Forecast System, version 2, and the Canadian Climate Model, version 3 (CanCM3), outperform other models in the sense that their squared error is less than that of other single models more frequently. It should be recognized that while certain models may be superior in a certain sense for a particular period and variable, combinations of forecasts are often significantly more skillful than a single model alone. In fact, the multimodel mean significantly outperforms all single models.

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Swedish politicians’ reflection of health effects for newly arrived migrants in decision-making

European Journal of Public Health ◽

10.1093/eurpub/ckaa166.1240 ◽

2020 ◽

Vol 30 (Supplement_5) ◽

Author(s):

S Svanholm ◽

H Carlerby ◽

E Viitasara

Keyword(s):

Decision Making ◽

General Population ◽

Health Effects ◽

Health Effect ◽

Determinants Of Health ◽

Rank Test ◽

The North ◽

Chi Squared ◽

Signed Rank Test ◽

Political Decisions

Abstract Background The political context of health promotion is important, however politicians' role has been sparsely researched. The aim was to explore whether politicians reflect on health effects of newly arrived migrants during political decision-making. Methods In total 667 politicians from municipalities and regional councils in the north of Sweden answered a web-based survey in 2019. The variable self-reported reflection of health effects during decision making in the last three months, focused on newly arrived migrants and the general population in the area, was used for analysis. Differences between political groups were analysed through Chi-squared test and differences in focus between the general population and newly arrived migrants were analysed by Wilcoxon Signed Rank Test. Results Preliminary results indicate that out of the participants 29,0% reported reflection on health effects for newly arrived migrants in large parts of their decisions, 50,5% having done so a few times, while 20,5% did not reflect. The politicians from the regions reported to a higher degree, compared to the municipality politicians, to have reflected on health effects (p = 0,003, Cramer's V = 0,136). Politicians more often considered the health effects of the general population in their decisions than for newly arrived migrants (z=-0,006, p < 0,001, r = 0,249). This difference remained when testing the municipality politicians (z=-7,417, p < 0,001, r = 0,228) and regional politicians (z=-5,138, p < 0,001, r = 0,346) separately. Conclusions Not all politicians reflect on the health effect of their decisions, especially not for newly arrived migrants' health. Politicians in the municipalities, responsible for many of the social determinants of health, did so to a lesser degree than the politicians in the regions, responsible for the healthcare system. The potential for politicians to promote health is thus not realized and political decisions can unintentionally affect health. Key messages Only a relatively small part of politicians considers health effects for newly arrived migrants in large parts of their decision-making. Municipality politicians, whose political decisions affect many determinants of health, consider health effects in a lesser degree than regional politicians do.

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Mass transportation problems with capacity constraints

Journal of Applied Probability ◽

10.1017/s002190020001723x ◽

1999 ◽

Vol 36 (02) ◽

pp. 433-445 ◽

Cited By ~ 2

Author(s):

S. T. Rachev ◽

I. Olkin

Keyword(s):

Joint Distribution ◽

Bivariate Distribution ◽

Capacity Constraints ◽

Distribution Functions ◽

Mass Transportation ◽

Marginal Distributions ◽

Transportation Problems ◽

The Family ◽

Additional Capacity ◽

Additional Constraints

We exhibit solutions of Monge–Kantorovich mass transportation problems with constraints on the support of the feasible transportation plans and additional capacity restrictions. The Hoeffding–Fréchet inequalities are extended for bivariate distribution functions having fixed marginal distributions and satisfying additional constraints. Sharp bounds for different probabilistic functionals (e.g.Lp-distances, covariances, etc.) are given when the family of joint distribution functions has prescribed marginal distributions, satisfies restrictions on the support, and is bounded from above, or below, by other distributions.

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IMPACT OF EDUCATION ON PATIENT ANXIETY BEFORE CATARAC OPERATION IN EYE HOSPITAL NORTH SULAWESI PROVINCE

Jurnal Ilmiah Perawat Manado (Juiperdo) ◽

10.47718/jpd.v6i1.785 ◽

2019 ◽

Vol 6 (1) ◽

pp. 22-31

Author(s):

Herman J. Warouw ◽

Semuel Tambuwun ◽

Graciela M. Pandeirot

Keyword(s):

Cataract Surgery ◽

Sampling Technique ◽

Rank Test ◽

P Value ◽

Test Results ◽

Patient Anxiety ◽

The North ◽

North Sulawesi ◽

Before And After ◽

Signed Rank Test

Background. Anxiety is a problem that often occurs in the preparation of cataract surgery patients in the hospital. In some cases the surgery is delayed due to patient anxiety. This study aims to determine the effect of education on patient anxiety in the preparation of the implementation of cataract surgery in the Eye Hospital of North Sulawesi Province. Method: This research is an experimental study using a One Group Pretest-Posttest design to compare patient anxiety before and after education. The number of samples used is 27 people obtained using purposive sampling technique. Data collection is done by filling out the questionnaire and then analyzed using the Wilcoxon Signed Rank Test. Results: The data showed that the anxiety of patients before being given education was 88.9% having moderate anxiety, 88.9% and after being given the greatest education (59.2% category of mild anxiety. Statistical test results showed there were differences in anxiety between before and after provided education to patients with cataract surgery preparations, with a P-value = 0,000 (α <0.05) Conclusion: there is an influence of education on patient anxiety in the preparation of cataract surgery at the North Sulawesi Province Eye Hospital. It is expected that patients before surgery need to be given education or information clearly so that patients do not feel anxious in the operation.

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SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157838 ◽

1990 ◽

Vol 48 (3) ◽

pp. 58-59

Author(s):

Daryl A. Cornish ◽

George L. Smit

Keyword(s):

Morphological Characteristics ◽

Oreochromis Mossambicus ◽

Breeding Cycle ◽

Limited Information ◽

North West ◽

The North ◽

Sem And Tem ◽

Sperm Development ◽

Ultrastructural Characteristics ◽

The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

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