Andrzej Matuszewski

Effects of CPAP treatment on psychological status in patients with severe obstructive sleep apnoea

The aim of this study was to evaluate the effects of nocturnal continuous positive airway pressure (CPAP) breathing on the emotional status and cognitive function in 20 patients with severe obstructive sleep apnoea (OSA) (mean±SD apnoea/hypopnoea index=67±16, mean overnight arterial oxygen saturation=83±10%). Psychological tests were performed before, after three, and after twelve months of CPAP treatment. At initial investigation, amongst cognitive functions, the most disturbed were concentration and recent memory. The majority of subjects demonstrated increased mental stress, depression, and anxiety. Anxiety correlated with AHI (r=0.68). Mental stress correlated with AHI (r=0.56) and deficiency of Stage 2 NREM sleep (r=−0.55). CPAP treatment resulted in significant improvement in cognitive function; concentration, recent verbal, visual and spatial memory were already seen at three months. No improvement in IQ and in emotional status after three months and one year of treatment was found. It is concluded that in patients with severe OSA CPAP treatment results in a significant early improvement in cognitive function but not in emotional status.

Models of Multiple Response Independence

We consider the problem of how to measure a “correlation” (or interdependence) between two survey-questionnaire questions. In the real-life questionnaires it is usual to offer several options-answers for most of the questions. Some (or many) questions give the possibility to choose more than one answer. There are very few statistical methods that enable inferences for the questions with multiple answers. We consider two statistics of the chi-square type that serve to confirm a dependence of two questions. As a theoretical basis a notion of “independence” between two multiple questions should be introduced. We propose two definitions (or actually types of definitions): “random” and “generalized Poisson” independences. A simulation study was performed, which is based on those notions. The study confirms applicability of the chi-square statistics, which are similar to the classical ones.

Dependence of Two Multiresponse Variables: Importance of The Counting Method

The problem of testing statistical hypotheses of independence of two multiresponse variables is considered. The final aim of the investigation is the formation of methods that discover relevant information existing in a database with (given) population survey results. We show in this research that a formulation of null hypothesis has an impact on p-values of a given subset of data. It is possible therefore to establish: a significant dependence of responses in one sense and a lack of such dependence in another sense. Such a discovery can be meaningful for producers of questionnaire surveys. Specific algorithms for automated data mining can be formulated that consider specific null hypotheses on independency or dependency of survey questions.

Evolutionary Real-Time Optimization System for Ecological Power Control

In this paper, Evolutionary Real-time Optimization System for Ecological Power Control for the area of Poland is presented. We describe the modeling issues of the problem, provide discussion on data used for the developed system, and introduce statistical methodology incorporated in the system. Finally, we describe evolutionary optimization system EROS and some experimental results.

You Must Be Cautious While Looking For Patterns With Multiresponse Questionnaire Data

The problem of testing statistical hypotheses of independence of two multiresponse variables is considered. This is a specific inferential environment to analyze certain patterns particularly for the questionnaire data. Data analyst normally looks for certain combination of responses being more frequently chosen than the other ones. As a result of experimental study we formulate some practical advices and suggest areas of further research.

Double Clustering: A Data Mining Methodology for Discovery of Causality

A generalization of the classical cluster analysis is proposed. From one point of view it is just a subsequent cluster analysis applied to the centers of clusters obtained in the first clustering. Such a double clustering procedure attains its effectiveness especially when a certain structure of causality (which often exists in the real, large data sets) is taken into account. Since we introduce a rather broad class of algorithms — which seems to be a quite general attempt — a very specific form of presentation is necessary. We present therefore methodology for a specific dataset to make the development of analysis and interpretation of its results more concrete.

Residuals for Two-Way Contingency Tables, Especially Those Computed forMultiresponces

The problem of testing statistical hypotheses of independence of two multiresponse variables is considered. This is a specific inferential environment to analyze certain patterns, particularly for the questionnaire data. Data analyst normally looks for certain combination of responses being more frequently chosen by responders than the other ones. A formalism that is adequate for the considerations of such a kind is connected with calculation of p-values within the so-called posthoc analysis. Since this analysis is often connected with one cell of an appropriate contingency table only, we consider residual (or deviate) of this cell. As a result of theoretical and experimental study we consider algorithms that can be effective for the problem. We consider the case of 2 × 3 tables. Some aspects are relevant also for classical i.e. uniresponsive contingency tables.

Critical Levels of Sulphur Dioxide in Poland and Their Exceedances

The statistical model based on cluster and regression analyses, were developed for calculating 5th percentile critical levels of sulphur dioxide for Poland. Model formulation, performance and results given in the computational grid representing a part of the EMEP model grid are presented. Current and past sulphur dioxide concentration fields were used for the calculations of critical levels exceedances. The obtained exceedances’ maps show that the threat to the ecosystems in Poland connected with sulphur dioxide air concentrations is declining.