In this paper we compute performance indices like those from Mereuta et all. (2007) using the eigenvalues and the eigenvectors of the variance-covariance matrix of these indices. The eigenvalues are used in this paper to give natural weights to the performance indices in order to compute the...

In this paper we classify competitive markets using a new form of normalized Herfindahl index and the degree of dominance of the leader. For this purpose we use the notion of copula, which connects two or more random variables with given marginals. The parameters of the two marginals (which are...

In this paper we will study the influence of qualitative variables on the unit root tests for stationarity. For the linear regressions involved the implied assumption is that they are not influenced by such qualitative variables. For this reason, after we have introduced such variables, we...

The Granger causality test is reduced, after co-integration, to the test of the fact that some coefficients of linear regressions are equal to zero or not. In this paper we will build multi-variate Bayes tests for the signification of the parameters of linear regression provided by the above...

In this paper we have found an analytical formula for a copula that connects the numbers Ni of customers in the nodes of a Gordon and Newell queueing network. We have considered two cases: the first one is the case of the network with 2 nodes, and the second one is the case of the network with...

In this paper we will classify patterns using an algorithm analogous to the k-means algorithm and the principal components regression (PCR). We will also present a financial application in which we apply PCR if the points represent the interests for accounts with different terms.

In this paper we will classify patterns using an algorithm analogous to the k-means algorithm and the regression polynomial of the degree k (for instance, if k=1 we obtain the regression line, and if k=2 we obtain the regression parable), and the regression hyper-plane. We will also present a...

In this paper we apply the Monte Carlo method to find the eigenvalues and the eigenvectors of a k-symmetric matrix A. At first we add to the main diagonal of A a real number large enough to obtain a covariance matrix B and we take into account that the minimum sum of the squares in the principal...

In this paper we will use the Bayesian inference for the parameters that appear in the queueing systems. We will estimate these parameters and we will build confidence intervals and significance tests for them, considering the parameters of the exponential Poisson and geometric distribution. We...

In this article we will determine the confidence regions for the parameters of a distribution and versions of some tests without using tables that contain centiles.