The EURPLN, DAX and WIG20: The Granger Causality Tests Before and During the Crisis

In this paper the possible interdependence between bilateral exchange rate behavior and the corresponding stock indices is checked, with application to the EURPLN rate and the DAX and WIG20 stock indices. Methods and results are similar to previous study of USDPLN exchange rate, and SP500 and WIG20 indices. The linear (including instantaneous) causality test and the Diks-Panchenko test are applied to logarithmic returns and to the  daily measure of volatility r(t) = ln(P(max,t)/P(min, t)). Differences between before- and during-crisis period results are less vivid than in case of the U.S. and the Polish instruments. But there is a substantial difference between linear (and Diks-Panchenko) test results and the instantaneous Granger-causality test results, on the other hand – between returns and daily volatility

Increasing role of arthropod bites in tularaemia transmission in Poland – case reports and diagnostic methods

The study describes four cases of tularaemia – one developed after contact with rabbits and three developed after an arthropod bite. Due to non-specific clinical symptoms, accurate diagnosis of tularaemia may be difficult. The increasing contribution of the arthropod vectors in the transmission of the disease indicates that special effort should be made to apply sensitive and specific diagnostic methods for tularaemia, and to remind health-care workers about this route of Francisella tularensis infections. The advantages and disadvantages of various diagnostic methods – molecular, serological and microbiological culture – are discussed. The PCR as a rapid and proper diagnostic method for ulceroglandular tularaemia is presented

Is Sustained Virological Response a Marker of Treatment Efficacy in Patients with Chronic Hepatitis C Viral Infection with No Response or Relapse to Previous Antiviral Intervention?

Background: Randomised clinical trials (RCTs) of antiviral interventions in patients with chronic hepatitis C virus (HCV) infection use sustained virological response (SVR) as the main outcome. There is sparse information on long-term mortality from RCTs.  Methods: We created a decision tree model based on a Cochrane systematic review on interferon retreatment for patients who did not respond to initial therapy or who relapsed following SVR. Extrapolating data to 20 years, we modelled the outcome from three scenarios: (1) observed medium-term (5 year) annual mortality rates continue to the long term (20 years); (2) long-term annual mortality in retreatment responders falls to that of the general population while retreatment non-responders continue at the medium-term mortality; (3) long-term annual mortality in retreatment non-responders is the same as control group non-responders (i.e., the increased treatment-related medium mortality “wears off”).  Results: The mean differences in life expectancy over 20 years with interferon versus control in the first, second, and third scenarios were -0.34 years (95% confidence interval (CI) -0.71 to 0.03), -0.23 years (95% CI -0.69 to 0.24), and -0.01 (95% CI -0.3 to 0.27), respectively. The life expectancy was always lower in the interferon group than in the control group in scenario 1. In scenario 3, the interferon group had a longer life expectancy than the control group only when more than 7% in the interferon group achieved SVR.  Conclusions: SVR may be a good prognostic marker but does not seem to be a valid surrogate marker for assessing HCV treatment efficacy of interferon retreatment. The SVR threshold at which retreatment increases life expectancy may be different for different drugs depending upon the adverse event profile and treatment efficacy. This has to be determined for each drug by RCTs and appropriate modelling before SVR can be accepted as a surrogate marker

GRANGER CAUSALITY – SELECTED METHODS

Definicja przyczynowości w sensie Grangera stanowi kompromis umożliwiający statystyczne testowanie tej zależności. Liniowa przyczynowość to zawężenie tego pojęcia, w istocie chodziło o zależności procesów generujących dane. Istnieją testy dla zmiennych niestacjonarnych, testy przyczynowości nieliniowej itd. Omawiamy niektóre z nich. W części empirycznej stosujemy nieliniowy test Diksa-Panchenki do szeregów finansowych w celu sprawdzenia, czy wyniki różnią się od wyników testu Grangera.Granger causality is defined to allow for construction of statistical tests. Granger himself intended to describe, possibly nonlinear, dependencies between data generating processes and take into account informational content of interdependence between variables. There are tests for nonstationary variables, of nonlinear causality etc., we describe some of the methods. We apply to daily returns of exchange rate and stock indices the linear Granger test and the Diks-Panchenko test (for nonlinear dependencies), while taking into account influence of the recent crisis

Are electromyographic patterns during gait related to abnormality level of the gait in patients with spastic cerebral palsy?

Purpose: One of the aims of the treatment in ambulant cerebral palsy (CP) patients is improvement of gait. Level of gait pathology is assessed by instrumented gait analysis, including surface electromyography. The aim of this study was to investigate the relation of the abnormality level of the gait and the co-contraction of the agonist-antagonist muscles, and relation between symmetry left /right leg in gait and symmetry of muscular activity. Methods: Fifty one patients with Cerebral Palsy underwent clinical assessment and instrumented gait analysis, including surface electromyography. Signals were bilaterally collected from rectus femoris, medial and lateral hamstrings, tibialis anterior, lateral gastrocnemius and gluteus maximus. In older children additionally signals from soleus and lateral vastus were recorded. Sixteen gait variables were selected to calculate Gillette Gait Index, separately for left and right leg. From the envelopes the series of cross-correlation coefficients were calculated. Results: Weak correlations were found between averaged agonist-antagonist correlation coefficient and Gillette Gait Index. Differences between hemiparetic less-involved legs, hemiparetic spastic legs, and diplegic legs were found for co-contraction of rectus femoris and biceps femoris and for averaged agonist-antagonist co-contraction. The differences between hemiparetic and diplegic groups were found for some muscle correlation coefficients. Conclusions: The results obtained in this study show, that the activity pattern of the leg muscles is specific for a given patient, and the dependence of the kinematics pathology on the abnormal activation pattern is not a direct one

Empirical power of the Kwiatkowski-Phillips-Schmidt-Shin test

The aim of this paper is to study properties of the Kwiatkowski-Phillips-Schmidt-Shin test (KPSS test), introduced in Kwiatkowski et al. (1992) paper. The null of the test corresponds to stationarity of a series, the alternative to its nonstationarity. Distribution of the test statistics is nonstandard, asymptotically converges to Brownian bridges as was shown in original paper. The authors produced tables of critical values based on asymptotic approximation. Here we present results of simulation experiment aimed at studying small sample properties of the test and its empirical power.KPSS test, stationarity, integration, empirical power of KPSS test

Financial crisis influence on the BUX index of Hungarian stock exchange. Long memory measures: 1991-2008

We analyze daily quotes of the BUX index, main index of the Budapest stock exchange, for period 2nd Jan. 1991–30th Sept. 2008, checking nonstationarity of series, stationarity of returns, applying the ARCH tests to the series. This period was not without its perils for the Hungarian economy. We check presence of long memory of the series with use of classification based on the Hurst index and fractional integration parameter estimates. We analyze sample ACF and PACF functions and fractional integration estimates also for squared returns of the index. Volatility of returns and squared returns increases towards the end of sample, in agreement with the fact of risk growth due to the global crisis. In last part of sample the series of returns was antipersistent, changing sign more often, and the series was more volatile. Graphs of spectrum for the series show different behavior of logarithmic returns (more volatile towards the end of sample) and similar for squared returns throughout the sample.Length: 21 pagesunit root, nonstationarity, spectral analysis, long memory, random walk, fractional integration, stock exchange index, volatility, risk