Regression Properties for Asymmetric Generalized Scale Mixtures of Multivariate Gaussian Variables

Analytical properties of regression and the variance–covariance matrix of asymmetric generalized scale mixture of multivariate Gaussian variables are presented. The analysis includes an in-depth analytical investigation of the first two conditional moments of the mixing variable. Exact computable expressions for the prediction and the conditional variance are presented for the generalized hyperbolic distribution using the inversion theorem for Fourier transforms. An application to financial log returns is demonstrated via the classical Euler approximation. The methodology is illustrated by analyzing the regression of intraday log returns for CISCO against the corresponding data from S&P 500.     

Determining Process Death Based on Censored Activity Data

This article addresses the problem of estimating the time of apparent death in a binary stochastic process. We show that, when only censored data are available, a fitted logistic regression model may estimate the time of death incorrectly. We improve this estimation by utilizing discrete-event simulation to produce simulated complete time series data. The proposed methodology may be applied to situations where time of death cannot be formally determined and has to be estimated based on prolonged inactivity. As an illustration, we use observed monthly activity patterns from 300 real Open Source Software development projects sampled from Sourceforge.net.     

Socioeconomic Indicators for Analyzing Convergence: The Case of Greece: 1960–2004

The purpose of this paper is to use socioeconomic indicators for analyzing convergence within Greece at regional (NUTS II) and prefecture levels (NUTS III) since 1960. We use two alternative approaches. The first one is based on the coefficient of variation and the second one on quality of life rankings. We confirm the decline of regional inequalities in Greece, with the exclusion of the 1980s. Regions with increased tourist and trade activity are also regions with high quality of life. Border regions are usually the laggards of social and economic development.

The conditional variance for gamma mixtures of normal distributions

This paper is concerned with obtaining an expression for the conditional variance-covariance matrix when the random vector is gamma scaled of a multivariate normal distribution. We show that the conditional variance is not degenerate as in the multivariate normal distribution, but depends upon a positive function for which various asymptotic properties are derived. A discussion section is included commenting on the usefulness of these results     

Gambling on Electronic Gaming Machines in Germany: An Age-Period-Cohort Analysis

To provide insights into etiological factors of gambling at the population level, it is critical to document the separate contributions of biological aging, period influences, and birth cohorts on observed temporal trends in gambling. This study investigated age, period, and cohort effects on prevalence rates of electronic gaming machine (EGM) gambling in Germany. We used data from a series of repeated cross-sectional surveys from the Federal Centre for Health Education covering the period 2007–2015. A total of 53,005 participants were surveyed about their past-year participation in EGMs. Using the intrinsic estimator, we disentangled the separate effects of age (16–17 to 64–65 years), period (2007, 2009, 2011, 2013, 2015), and birth cohort (1941–42 to 1997–98). Age effects were highest for those aged 18–33 (p < 0.001). Period effects were highest in 2013 and lowest in 2015 (p < 0.005). A significant increasing birth cohort effect was evident in cohorts born between 1985 and 1998 (p < 0.005). Implications of these results are discussed with regard to the vulnerability of younger ages to gambling, period changes in the regulatory framework of Germany, and differential cohort vulnerability of the Millennial generation due to early-life video gaming experiences.     

Change-point mle in the rate of exponential sequences with application to Indonesian seismological data

In this paper, we derive explicit computable expressions for the asymptotic distribution of the maximum likelihood estimate of an unknown change-point in a sequence of independently and exponentially distributed random variables. First we state and prove a theorem that shows asymptotic equivalence of the change-point mle for the cases of both known and unknown parameters, respectively. Thereafter, the computational form of the asymptotic distribution of the change-point mle is derived for the case of known parameter situation only. Simulations show that the distribution for the known case applies very well to the case where the parameters are estimated. Further, it is seen from simulations that the derived unconditional mle shows better performance compared to the conditional solution of Cobb. Application of change detection methodology and the derived estimation methodology show strong support in favor the dynamic triggering hypothesis for seismic faults in Sumatra, Indonesia region.     

Asymptotic study of the change-point mle in multivariate Gaussian families under contiguous alternatives

The problem of estimating an unknown change-point in the mean vector or covariance matrix of a sequence of independent multivariate Gaussian random variables is considered. Adapting the estimation methodology that Hinkley pursued for the case of abrupt changes, we develop theory for deriving the asymptotic distribution of the maximum likelihood estimator of the change-point when the amount of change is a function of the sample size and goes to zero in a smooth fashion as the sample size goes to infinity, yielding a contiguous change-point model. Simulations have been performed to illustrate the closeness of the asymptotic distribution with the empirical distribution, and to evaluate its robustness to departures from normality for reasonable sample sizes as well as parameter changes. Finally, we apply the methodology to estimate the change-point in the daily log-returns data of BLS (BellSouth) and VZ (Verizon) from NYSE.