Understanding Uncertainty Shocks

Abstract For decades, macroeconomists have searched for shocks that are plausible drivers of business cycles. A recent advance in this quest has been to explore uncertainty shocks. Researchers use a variety of forecast and volatility data to justify heteroskedastic shocks in a model, which can then generate realistic cyclical fluctuations. But the relevant measure of uncertainty in most models is the conditional variance of a forecast. When agents form such forecasts with state, parameter and model uncertainty, neither forecast dispersion nor innovation volatilities are good proxies for conditional forecast variance. We use observable data to select and estimate a forecasting model and then ask the model to inform us about what uncertainty shocks look like and why they arise. Some times feel like uncertain times for the aggregate economy. At other times, events appear to be predictable, volatility is low, confidence is high. An active emerging literature argues that changes in uncertainty can explain business cycle fluctuations, stock prices, and banking crises. Uncertainty shocks are typically modeled as volatility shocks. Authors assume that a shock (e.g. productivity) is drawn from a distribution whose variance changes over time. Sometimes the high and low volatility are calibrated to match the size of business cycles. Other times, they are matched to features of macro forecast data, the volatility index (VIX) or uncertainty proxies. This paper seeks to clarify the relationship between uncertainty an commonly-used measures of uncertainty. We show that when agents consider the possibility that their model might be wrong, uncertainty, volatility and forecast errors are conceptually distinct

Understanding Uncertainty Shocks

Abstract For decades, macroeconomists have searched for shocks that are plausible drivers of business cycles. A recent advance in this quest has been to explore uncertainty shocks. Researchers use a variety of forecast and volatility data to justify heteroskedastic shocks in a model, which can then generate realistic cyclical fluctuations. But the relevant measure of uncertainty in most models is the conditional variance of a forecast. When agents form such forecasts with state, parameter and model uncertainty, neither forecast dispersion nor innovation volatilities are good proxies for conditional forecast variance. We use observable data to select and estimate a forecasting model and then ask the model to inform us about what uncertainty shocks look like and why they arise. Some times feel like uncertain times for the aggregate economy. At other times, events appear to be predictable, volatility is low, confidence is high. An active emerging literature argues that changes in uncertainty can explain business cycle fluctuations, stock prices, and banking crises. Uncertainty shocks are typically modeled as volatility shocks. Authors assuming that a shock (e.g. productivity) is drawn from a distribution whose variance changes over time. Sometimes the high and low volatility are calibrated to match the size of business cycles. Other times, they are matched to features of macro forecast data, the volatility index (VIX) or uncertainty indices. We define macroeconomic uncertainty as the variance of next-period GDP growth y t+1 , conditional on all information observed through time-t: V ar[y t+1 |I t ]. We use this definition because in most models, this is the theoretically-relevant moment. When there is an option * Preliminary draft. Please send comments to [email protected] and [email protected]

Primary perforating dermatoses – current status

Primary perforating dermatoses (PPD) are a group of skin diseases rarely seen in everyday dermatological practice, which includes elastosis perforans serpiginosa, reactive perforating collagenosis, Kyrle disease and perforating folliculitis. These entities can be associated with chromosomal aberrations, chronic renal, cardiovascular or hepatic diseases. Unique histopathological findings in each PPD are useful in determination of the diagnosis. However, in other more frequently seen dermatoses of heterogeneous etiology, perforation of epidermis with material undergoing transepidermal elimination is also observed. Our article aims to present the most important recent information on epidemiology, pathogenesis, clinical findings, therapeutic options and differential diagnosis of primary perforating dermatoses

Nebulisation Therapy in Patients with Cystic Fibrosis—Consensus of the Polish Cystic Fibrosis Society

Introduction: Nebulisation therapy plays a key role in the treatment of cystic fibrosis (CF). Its effectiveness depends on obtaining a high concentration of drugs in the respiratory tract. Particle deposition is determined by many factors resulting, inter alia, from the essence of the lung disease (mucus, structural changes such as bronchiectasis, fibrous changes, cirrhosis) and the quality of the aerosol and breathing techniques during the procedure. Aims: A large variety of available drugs that can be used in the form of aerosols (bronchodilators, mucolytics, antibiotics), a wide range of devices for their delivery, and a different approach to the practical aspect related to the use of inhalation, makes it necessary to systematize knowledge in order to optimize nebulisation therapy. The paper presents an overview of inhaled drugs used in cystic fibrosis and their administration devices. Results: The principles of inhalation antibiotic therapy, which constitute the basis for the treatment of primary and chronic respiratory tract infections of Pseudomonas aeruginosa etiology, are discussed in detail. A very important issue was raised related to the proper selection of devices and their proper operation. In the context of the key role of nebulisation therapy in cystic fibrosis, a huge problem is the limited availability of inhaled antibiotics in Poland. Conclusions: The possibility of choosing an antibiotic and using alternating therapy increases the effectiveness of inhalation treatment, which results in slowing down the progress of bronchopulmonary disease and extending the life of patients

Nebulisation therapy in patients with cystic fibrosis — consensus of the Polish Cystic Fibrosis Society

Introduction: Nebulisation therapy plays a key role in the treatment of cystic fibrosis (CF). Its effectiveness depends on obtaining a high concentration of drugs in the respiratory tract. Particle deposition is determined by many factors resulting, inter alia, from the essence of the lung disease (mucus, structural changes such as bronchiectasis, fibrous changes, cirrhosis) and the quality of the aerosol and breathing techniques during the procedure. Aim of the Guidelines: A large variety of available drugs that can be used in the form of aerosols (bronchodilators, mucolytics, antibiotics), a wide range of devices for their delivery, and a different approach to the practical aspect related to the use of inhalation, makes it necessary to systematize knowledge in order to optimize nebulisation therapy. The paper presents an overview of inhaled drugs used in cystic fibrosis and their administration devices. Results: The principles of inhalation antibiotic therapy, which constitute the basis for the treatment of primary and chronic respiratory tract infections of Pseudomonas aeruginosa etiology, are discussed in detail. A very important issue was raised related to the proper selection of devices and their proper operation. In the context of the key role of nebulisation therapy in cystic fibrosis, a huge problem is the limited availability of inhaled antibiotics in Poland. Conclusions: The possibility of choosing an antibiotic and using alternating therapy increases the effectiveness of inhalation treatment, which results in slowing down the progress of bronchopulmonary disease and extending the life of patients