Forecasting economic activity using preselected predictors: the case of Cyprus

This paper applies hard and soft thresholding techniques to a large dataset of domestic and foreign series in order to preselect informative predictors for forecasting economic activity in Cyprus. The variables of interest in the forecasting exercise consist of GDP and the production-side components of GDP, expressed in growth rates. The subsets of selected predictors are allowed to differ across the variables of interest and over the forecast horizon, thus accommodating idiosyncratic features of economic sectors. The sets of selected predictors contain a higher proportion of domestic as opposed to foreign predictors for the one-quarter horizon, while the opposite occurs for longer horizons. Furthermore, in the case of GDP all thresholding techniques result in selecting high proportions of business and consumer survey indicators for all horizons. The forecasting performance depends on the forecast horizon and, most importantly, on whether the subsets of chosen predictors remain constant or change over time. The thresholding technique employed is not found to substantially affect the forecasting performance. Selecting predictors prior to forecasting GDP growth, leads to lower forecast errors vis-à-vis a simple univariate benchmark, as well as compared to exploiting the full dataset of predictors for forecasting. The gains from preselecting predictors are higher during a crisis period than in normal times, especially for short horizons, while preselection in normal times benefits forecast accuracy for longer horizons. Predictor preselection is found to improve the forecasting performance in the case of some production-side components, particularly the gross value added in the sectors of trade and construction, and net taxes

Rationale in diagnosis and screening of atrophic gastritis with stomach-specific plasma biomarkers

BACKGROUND AND AIMS: Atrophic gastritis (AG) results most often from Helicobacter pylori (H. pylori) infection. AG is the most important single risk condition for gastric cancer that often leads to an acid-free or hypochlorhydric stomach. In the present paper, we suggest a rationale for noninvasive screening of AG with stomach-specific biomarkers. METHODS: The paper summarizes a set of data on application of the biomarkers and describes how the test results could be interpreted in practice. RESULTS: In AG of the gastric corpus and fundus, the plasma levels of pepsinogen I and/or the pepsinogen I/pepsinogen II ratio are always low. The fasting level of gastrin-17 is high in AG limited to the corpus and fundus, but low or non-elevated if the AG occurs in both antrum and corpus. A low fasting level of G-17 is a sign of antral AG or indicates high intragastric acidity. Differentiation between antral AG and high intragastric acidity can be done by assaying the plasma G-17 before and after protein stimulation, or before and after administration of the proton pump inhibitors (PPI). Amidated G-17 will rise if the antral mucosa is normal in structure. H. pylori antibodies are a reliable indicator of helicobacter infection, even in patients with AG and hypochlorhydria. CONCLUSIONS: Stomach-specific biomarkers provide information about the stomach health and about the function of stomach mucosa and are a noninvasive tool for diagnosis and screening of AG and acid-free stomach