Libri in offerta

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.

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.

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

This paper aims to show to what extent self-perception of poverty is affected by respondent/household socio-economic characteristics and by social capital endowment of household place of residence in order to disclose the primary risk factors of family poverty status. Such evidence would help central and local government to define those economic and social goals which should receive more attention by current policies with the purpose of advancing towards the eradication of poverty. In order to purse this aim the logit model has been applied to analyze answers to the dichotomous transformation of the following question taken from the 2008 Survey on Household Income and Wealth (SHIW) of the Bank of Italy CONSIDERING YOUR MONTHLY DISPOSABLE INCOME, IS YOUR HOUSEHOLD ABLE TO MAKE ENDS MEET: (1) WITH GREAT DIFFICULTY, (2) WITH DIFFICULTY, (3) WITH SOME DIFFICULTY, (4) WITHOUT DIFFICULTY, (5) WITH EASE, (6) WITH GREAT EASE? The results show a relevant effect on self-perception of poverty of both respondent /household socio-economic characteristics and social capital. In particular, the components social relationships and social engagement contribute to reduce the risk of a self-perceived poverty. Actually, networks characterized by relationships of trust are key determinants of human welfare as people socio-economic vulnerability is reduced as well as the resources they need only for the fact that they must deal with risk and avert major losses. Keywords: Self-perception of Poverty, Social Capital, Household Socio-Economic Characteristics, Policy-Makers