Comments on “Canonical Correlation in Multivariate Time Series Analysis With an Application to One-Year-Ahead and Multiyear- Ahead Macroeconomic Forecasting,” by P. W. Otter

We examine the orthogonality assumption of seasonal and nonseasonal components for official quarterly unemployment figures in Germany and the United States. Although nonperiodic correlations do not seem to reject the orthogonality assumption, a periodic analysis based on correlation functions that vary with the seasons indicates the violation of orthogonality. We find that the unadjusted data can be described by periodic autoregressive models with a unit root. In simulations we replicate the empirical findings for the German data, where we use these simple models to generate artificial samples. Multiplicative seasonal adjustment leads to large periodic correlations. Additive adjustment leads to smaller ones.     

Unmet needs at the end of life: perceptions of hospice social workers

Among persons at the end of life, it is important to understand whether the needs of patients are being adequately addressed. In particular, in hospice settings where the emphasis is on comfort care and quality of life, we know little about the presence of unmet needs. The purpose of this study was to examine the experiences of hospice social workers in working with hospice patients who had unmet needs at the end of life. Surveys were mailed to hospice social workers (N = 212) in two Southeastern states with a response rate of 36%. Results revealed that hospice social workers perceived patients to experience a wide variety of unmet needs-more commonly at the time of admission than during subsequent patient interactions. The most common unmet need reported at both times was a decreased ability to participate in activities that make life enjoyable. In situations where unmet needs exist, social workers reported that the most common perceived reasons were patient- related psychosocial issues and family conflict/issues. Additionally, a variety of interventions were used to address unmet needs, but a large number of barriers appear to impact outcomes in the cases. Results suggest that hospice patients experience a number of unmet needs, many of which are potentially treatable problems and concerns. Hospice professionals must continue to seek ways to assess and intervene effectively with patients who have unmet needs.     

Distributions with Generalized Skewed Conditionals and Mixtures of Such Distributions

Mixtures of skewed distributions (univariate and bivariate) provide flexible models. An alternative modeling approach involves distributions with skewed conditional distributions and mixtures of such distributions. We consider the interrelationships between such models. Examples are provided to show that several skewed distributions already considered in the literature can be viewed as having been constructed via a combination of mixing and skewing.     

Asymptotics of improved generalized moment estimators for spatial autoregressive error models

Abstract

This article considers linear models with a spatial autoregressive error structure. Extending Arnold and Wied (2010) Arnold, M., Wied, D. (2010). Improved GMM estimation of the spatial autoregressive error model. Econ. Lett. 108:65–68.[Crossref], [Web of Science ®] , [Google Scholar], who develop an improved generalized method of moment (GMM) estimator for the parameters of the disturbance process to reduce the bias of existing estimation approaches, we establish the asymptotic normality of a new weighted version of this improved estimator and derive the efficient weighting matrix. We also show that this efficiently weighted GMM estimator is feasible as long as the regression matrix of the underlying linear model is non stochastic and illustrate the performance of the new estimator by a Monte Carlo simulation and an application to real data.     

The height of two types of generalised Motzkin paths

Consider Motzkin paths which are lattice paths in the plane starting at the origin, running weakly above the x-axis and after n   unit steps returning at the point (n,0)$(n,0)$. The allowed steps are the up and down steps (1,1)$(1,1)$ and (1,−1)$(1,-1)$ respectively and certain horizontal steps. We consider two types of horizontal steps that have attracted recent attention in the literature. First, we consider unit horizontal steps (1,0)$(1,0)$ coloured with k colours, secondly, we look at paths where the horizontal steps are of length k, for a non-negative integer k. Using generating functions, we study the sum of heights of such paths of size n. With the use of the Mellin transform, we find asymptotic expressions for the mean heights as n tends to infinity.     

Editorial Statement

A recently developed statistical model, called Bayesian vector autoregression, has proven to be a useful tool for economic forecasting. Such a model today forecasts a strong resurgence of growth in the second half of 1985 and in 1986.     

On the robustness of x-charts

In process control the simple x-charts are widely used. In determining an optimum economic design for such a control procedure the time of satisfactory production is usually assumed to be exponentially distributed. In this paper deviations from this optimistic approach are investigated by comparing E-optimal x-charts (using the assumption of an exponentially distributed lifetime) and M-optimal x-charts which are obtained by tfie pessimistic muumax principle applied to all possible lifetime distributions with the same mean value. The comparison shows that the differences between E- and M-optimal x-charts are only minor with respect to a suitable loss function and therefore, the model under consideration is verv robust against deviations from the assumption about the distribution of the time of satisfactory production.