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Libri in offerta

EDITORIALE: Una triplice perseveranza
Gratis
digital
formato: Articolo | LA RIVISTA DEL CLERO ITALIANO - 2011 - 7-8
Anno: 2011
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Introduzione
Gratis
digital
formato: Articolo | STUDI DI SOCIOLOGIA - 2011 - 3
Anno: 2011
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EDITORIALE: «Purché conduca a termine la mia corsa»
Gratis
digital
formato: Articolo | LA RIVISTA DEL CLERO ITALIANO - 2011 - 6
Anno: 2011
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EDITORIALE: Il coraggio della fede
Gratis
digital
formato: Articolo | LA RIVISTA DEL CLERO ITALIANO - 2011 - 5
Anno: 2011
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Sommario generale dell'annata
Gratis
digital
formato: Articolo | STUDI DI SOCIOLOGIA - 2011 - 4
Anno: 2011
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Sommario generale dell’annata
Gratis
digital
formato: Articolo | RIVISTA DI FILOSOFIA NEO-SCOLASTICA - 2011 - 4
Anno: 2011
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EDITORIALE: Passione e Risurrezione
Gratis
digital
formato: Articolo | LA RIVISTA DEL CLERO ITALIANO - 2011 - 4
Anno: 2011
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Chi-Square goodness of fit test for logistic distribution using RSS and SRS
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2011 - 2
Anno: 2011
In this paper, we introduce a new method to improve the power of the chi-square test for goodness of fit (GOF) of logistic distribution under selective order ranked Set sampling (RSS) based on minimum, median and maximum as compared to simple random sampling (SRS). Based on a simulation study, we illustrate that the chi-square test is found to be more powerful under selective order RSS when compared to SRS, particularly for minimum and maximum. However, for the case of median RSS, the test is found to be more powerful under SRS. To investigate these results further, the Kullback- Leibler information (KLI) is applied and similar results are found. Keywords: Goodness of fit test, chi-square test, logistic distribution, ranked set sample, simple random sample.
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Point and interval estimation for some financial performance measures
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2011 - 2
Anno: 2011
We study the estimators of three financial performance measures: the Sharpe Ratio, the Mean Difference Ratio and the Mean Absolute Deviation Ratio. The analysis is performed under two sets of assumptions. First, the case of i.i.d. Normal returns is considered. After that, relaxing the normality assumption, the case of i.i.d. returns is investigated. In both situations, we study the bias of the estimators and we propose their bias-corrected version. The exact and asymptotic distribution of the three estimators is derived under the assumption of i.i.d. Normal returns. Concerning the case of i.i.d. returns, the asymptotic distribution of the estimators is provided. The latter distributions are used to define exact or asymptotic confidence intervals for the three indices. Finally, we perform a simulation study in order to assess the efficiency of the bias corrected estimators, the coverage accuracy and the length of the asymptotic confidence intervals. Keywords: Financial Performance Measure, Sharpe Ratio, Mean Difference Ratio, Mean Absolute Deviation Ratio, Concentration Measures, Statistical Analysis of Financial Data.
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Improved group acceptance sampling plans for the gamma distributed items
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2011 - 2
Anno: 2011
In this paper, a time truncated group acceptance sampling plan (GASP) is designed under the Gamma distribution. The present plan is modification of the existing plan to reduce the number of groups/sample size. The plan parameters are obtained by satisfying the producer’s risk and consumer’s risk (two points approach) for specified values of mean ratio and number of testers. The single point approach is also used to find plan parameters such as number of groups for specified values of acceptance number and experiment time. The extensive tables, graphs and examples are given for illustration purposes. The advantage of the proposed plan discussed over the existing plans. Keywords: Group Acceptance Sampling; Consumer’s Risk; Producer’s Risk; Gamma Distribution; Operating Characteristic Values.
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The Confidence Ellipses in Multiple Non-Symmetrical Correspondence Analysis for the Evaluation of the Innovative Performance of the manufacturing enterprises in Campania
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2011 - 2
Anno: 2011
Non-Symmetric Correspondence Analysis-NSCA (D’Ambra and Lauro, 1989) is a useful technique for analyzing a two-way contingency table. There are many real-life applications where it is not appropriate to perform classical correspondence analysis because of the obvious asymmetry of the association between the variables. The key difference between the symmetrical and non-symmetrical versions of correspondence analysis rests on the measure of the association used to quantify the relationship between the variables. For a two-way, or multi-way, contingency table, the Pearson chisquared statistic is commonly used when it can be assumed that the categorical variables are symmetrically related. However, for a two-way table, it may be that one variable can be treated as a predictor variable and the second variable can be considered as a response variable. Yet, for such a variable structure, the Pearson chi-squared statistic is not an appropriate measure of the association. Instead, one may consider the Goodman-Kruskal tau index. In the case that there are more than two cross-classified variables, multivariate versions of the Goodman-Kruskal tau index can be considered. These include Marcotorchino’s index (Marcotorchino, 1985) and Gray-Williams’ index (Gray and Williams, 1975). In the present paper, the Multiple non- Symmetric Correspondence Analysis- MNSCA (Gray and Williams, J. S,1975), is used for the evaluation of the innovative performance of the manufacturing enterprises in Campania. Innovation represents a very important element for the competition of the enterprises and economic growth. Only the enterprises which are able to innovate regularly can have at their disposal a range of more and more appealing products for the customers. Moreover, only a constant innovation provides the constant efficiency of the processes and the optimization of the production costs. Finally, the use of the ellipse confidence has allowed to identify a category which is statistically significant. Keywords: CATANOVA, Confidence Ellipse, Gray-Williams Multiple Tau Index, Multiple Non Symmetrical Correspondence Analysis
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The effect of education and ability. An estimation on the labour income of Italian graduates
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2011 - 2
Anno: 2011
In this paper we present a method for estimating the effect of college education independent of individual ability. We use a matching procedure to compare graduates and high school diploma holders (the latter to be used as counterfactuals) in order to identify both treatment and ability parameters in a two-regime equation model. A sensitivity analysis suggests that our matching results are robust with respect to a possible bias due to unobserved heterogeneity. Using Istat’s Survey on Italian Graduates, we estimate that the average effect of one year of college attendance on labour income is close to 7.5%. Unlike the results reported in recent literature, the effect of education is not higher for better endowed individuals. Keywords: Ability Bias, Matching, Treatment Effects Estimation, Two-Regime Regression Model.
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