Block bootstrap for periodic characteristics of periodically correlated time series

This research is dedicated to the study of periodic characteristics of periodically correlated time series such as seasonal means, seasonal variances and autocovariance functions. Two bootstrap methods are used: the extension of the usual Moving Block Bootstrap (EMBB) and the Generalised Seasonal Block Bootstrap (GSBB). The first approach is proposed, because the usual Moving Block Bootstrap does not preserve the periodic structure contained in the data and cannot be applied for the considered problems. For the aforementioned periodic characteristics the bootstrap estimators are introduced and consistency of the EMBB in all cases is obtained. Moreover, the GSBB consistency results for seasonal variances and autocovariance function are presented. Additionally, the bootstrap consistency of both considered techniques for smooth functions of the parameters of interest is obtained. Finally, the simultaneous bootstrap confidence intervals are constructed. A simulation study to compare their actual coverage probabilities is provided. A real data example is presented.     

Assessment of frailty syndrome using Edmonton frailty scale in Polish elderly sample

The aim of the study was to assess the incidence and severity of the frailty syndrome assessed with the Edmonton Frailty Scale. This is a cross-sectional study conducted among 382 patients (236 men and 146 women, mean age 71.9?years). The Edmonton Frailty Scale was administered during the patient’s admission to the hospital. The Polish adaptation was performed using the standard methodology. The Cronbach’s alpha coefficient for the whole Edmonton Frailty Scale was 0.709. The mean correlation between positions and the overall result was r?=?0.180. There were no statistically significant differences between women and men in the area of Edmonton Frailty Scale mean score (p?70?years than for those?<70?years (p?相似文献   

Generality of observational skill across verbal and nonverbal modes: Literature review and experimental test

The resurgence of interest in observational skills and in the generality or specificity of those skills is credited to recent research on individual differences in abilities to decode nonverbal messages. The issues involved in identifying general and specific factors of accuracy are traced to developments in earlier research on observation and to events that shaped contemporary negativism toward observers. An experiment on observational generality, across two different observational settings and three types of observational cues illustrates how easily either bias — toward generality or specificity of skills — can be demonstrated.     

On concave entropies of discrete systems

A new class of entropy functions of discrete systems, the class of concave entropies, is introduced. Each concave entropy function satisfies the fundamental axioms of general entropies. The Shannon and trigonometric entropies belong to the class of concave entropies. Each of the classes of Renyi and polynomial entropies contains a subclass of concave entropies. A sufficient condition is given, under which the total entropy tends to ∞, when the number N of probability components approaches ∞.     

Pathways to productivity improvement

A study of productivity in the Machine Tool industry has just been published by the Engineering Employers Federation (EEF). As a member of the Productivity Steering Group, information was available to one of the authors, in an unusually detailed and validated form for the twenty or so individual companies, (though they remain anonymous). It was thought worthwhile to apply methods developed in the Economics and Statistics Department of British Aerospace to this data in order to give pointers to the factors explaining productivity differences. The particular methods referred to were those of the Diagnostic Chart, though considerably simplified to match the data available, and multiple regression analysis. Particular care is necessary in applying the latter technique in productivity analysis if spurious results are to be excluded. The conclusions were as follows: the most favoured path to improved productivity is via increased turnover; changes in productivity are reflected mainly in changes in the ‘profit’ element of value added rather than in the labour cost element; the major factor distinguishing low from high productivity companies is an excess of the manual work force in relation to turnover; increased fixed assets favours increased labour productivity; increased commitment to R & D favours increased labour productivity; these conclusions are, of course, deduced from a study of the machine tool industry in particular, but may well be of applicability to other industries.