by Sameer A. Al-Subh, Mohd T. Alodat, Kamarulzaman Ibrahim, Abdul A. Jemain
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
by Lucio De Capitani, Michele Zenga
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.
by Amjad Daifalla Al-Nasser, Muhammad Aslam, Ahmed Bani-Mustafa, Maryam Fatima
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.
by Anna Crisci, Antonello D'Ambra
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
by Antonino Di Pino, Patrizia Pulejo
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.
by Isabella Santini
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
Keywords: Self-perception of Poverty, Social Capital, Household Socio-Economic Characteristics,