The Financial Crisis in Japan – Are There Similarities to the Current Situation?

Finanzmarktkrise, Bankenkrise, Bubbles, Immobilienmarkt, Aktienmarkt, Vergleich, Japan, Vereinigte Staaten, Financial crisis, Banking crisis, Real estate market, Stock market, Comparison, United States

The Virtues of VAR Forecast Pooling – A DSGE Model Based Monte Carlo Study

Since the seminal article of Bates and Granger (1969), a large number of theoretical and empirical studies have shown that pooling different forecasts of the same event tends to outperform individual forecasts in terms of forecast accuracy. However, the results remain heterogenous regarding the size of gains. As there are numerous sources for the large variation of the resulting gains, it is difficult to estimate the improvement in accuracy based on empirical findings. Consequently, we use Monte Carlo techniques which enable us to identify the gains of pooling from VAR forecasts under lab conditions. In particular, the results are allowed to vary with respect to sample size, forecast horizon, number of pooled forecasts, weighting scheme and structure of the model economy. Given strict lab conditions, our setup of the experiment yields a quantification of the virtues that can be obtained in almost any forecast situation. The analysis shows that pooling leads to a substantial reduction of MSE of about 20%, which is comparable to the elimination of estimation uncertainty. Most notably, this reduction is already obtained with an average of about four different forecasts.Pooling of forecasts, model uncertainty, VAR model, Monte Carlo Study

Log versus level in VAR forecasting: 16 Million empirical answers - expect the unexpected

The use of log-transformed data has become standard in macroeconomic forecasting with VAR models. However, its appropriateness in the context of out-of-sample forecasts has not yet been exposed to a thorough empirical investigation. With the aim of filling this void, a broad sample of VAR models is employed in a multi-country setup and approximately 16 Mio. pseudo-out-of-sample forecasts are evaluated. The results show that, on average, the knee-jerk transformation of the data is at best harmless.VAR-forecasting, logarithmic transformation

Estimating the effects of oil price shockson the Kazakh economy

This paper explores the role of oil for the Kazakh economy. In order to assess thedegree of volatility the oil price features, it, firstly, discusses the literature on oil price behaviour. Secondly, it analyzes the effect of oil price declines on key macroeconomicvariables such as real GDP, inflation and real exchange rates using vectorautoregressive (VAR) models. In this respect, the paper deviates from a large number of papers on oil price effects as it considers a transition rather than a developed economy and an oil exporting rather than an oil importing country. The key findings to emerge from this paper are, first, that the price of oil is influenced by a large number of factors, which results in a considerable degree of volatility. Secondly, all variables considered in theVAR model exhibit a strong negative significant reaction on oil price declines, and, thirdly, a standard linear VAR model is appropriate for capturing the Kazakh oil-macro relationship.Oil price, VAR-Models, oil exporting economy.

The vacuum bell for treatment of pectus excavatum: an alternative to surgical correction?

Objective: Pectus excavatum (PE) is the most common chest wall malformation and one of the most frequent major congenital anomalies. The surgical repair of PE in childhood is a well-established procedure. Previously used operative techniques to correct PE were largely based on the Ravitch technique. Today, the minimally invasive repair (MIRPE) by Nuss is well established. Conservative treatment with the vacuum bell to elevate the funnel in patients with PE represents a potential alternative. Methods: A suction cup is used to create a vacuum at the anterior chest wall. A patient-activated hand pump is used to reduce the pressure up to 15% below atmospheric pressure. Three different sizes of vacuum bell exist which are selected according to the individual patients age. When creating the vacuum, the lift of the sternum is obvious and remains for a different time period. The device should be used for a minimum of 30 min (2 per day), and may be used up to a maximum of several hours daily. Presently, a 12-15-month course of treatment is recommended. In addition, the device was used intraoperatively during the MIRPE procedure to enlarge the retrosternal space to ensure safer passage of the introducer in a few patients. Results: Thirty-four patients (31 males, 3 females), aged 6-52 years (median 17.8 years) used the vacuum bell for 1 to maximum 18 months (median 10.4 months). Follow-up included photography and clinical examination every 3 months. Computed tomographic scans showed that the device lifted the sternum and ribs immediately. In addition, this was confirmed thoracoscopically during the MIRPE procedure. After 3 months, an elevation of more than 1.5 cm was documented in 27 patients (79%). After 12 months, the sternum was lifted to a normal level in five patients (14.7%). Relevant side effects were not noted. Conclusions: The vacuum bell has proved to be an alternative therapeutic option in selected patients with PE. The initial results proved to be dramatic, but long-term results are so far lacking, and further evaluation and follow-up studies are necessary. In addition, the method may assist the surgeon during the MIRPE procedur

Rate and Pulse Based Plasticity Governed by Local Synaptic State Variables

Classically, action-potential-based learning paradigms such as the Bienenstock–Cooper–Munroe (BCM) rule for pulse rates or spike timing-dependent plasticity for pulse pairings have been experimentally demonstrated to evoke long-lasting synaptic weight changes (i.e., plasticity). However, several recent experiments have shown that plasticity also depends on the local dynamics at the synapse, such as membrane voltage, Calcium time course and level, or dendritic spikes. In this paper, we introduce a formulation of the BCM rule which is based on the instantaneous postsynaptic membrane potential as well as the transmission profile of the presynaptic spike. While this rule incorporates only simple local voltage- and current dynamics and is thus neither directly rate nor timing based, it can replicate a range of experiments, such as various rate and spike pairing protocols, combinations of the two, as well as voltage-dependent plasticity. A detailed comparison of current plasticity models with respect to this range of experiments also demonstrates the efficacy of the new plasticity rule. All experiments can be replicated with a limited set of parameters, avoiding the overfitting problem of more involved plasticity rules