Statistically Stable Estimates of Variance in Radioastronomical Observations as Tools for RFI Mitigation

A selection of statistically stable (robust) algorithms for data variance calculating has been made. Their properties have been analyzed via computer simulation. These algorithms would be useful if adopted in radio astronomy observations in the presence of strong sporadic radio frequency interference (RFI). Several observational results have been presented here to demonstrate the effectiveness of these algorithms in RFI mitigation

Who knows what when? : The information content of pre-IPO market prices : [Version March/June 2002]

To resolve the IPO underpricing puzzle it is essential to analyze who knows what when during the issuing process. In Germany, broker-dealers make a market in IPOs during the subscription period. We examine these pre-issue prices and find that they are highly informative. They are closer to the first price subsequently established on the exchange than both the midpoint of the bookbuilding range and the offer price. The pre-issue prices explain a large part of the underpricing left unexplained by other variables. The results imply that information asymmetries are much lower than the observed variance of underpricing suggests

Importing Corruption Culture from Overseas: Evidence from Corporate Tax Evasion in the United States

This paper studies how cultural norms and enforcement policies influence illicit corporate activities. Using confidential IRS audit data, we show that corporations with owners from countries with higher corruption norms engage in higher amounts of tax evasion in the U.S. This effect is strong for small corporations and decreases as the size of the corporation increases. In the mid-2000s, the United States implemented several enforcement measures which significantly increased tax compliance. However, we find that these enforcement efforts were less effective in reducing tax evasion by corporations whose owners are from countries with higher corruption norms. This suggests that cultural norms can be a challenge to legal enforcement.

Robust correlators

Radio frequency interference (RFI) already limits the sensitivity of existing radio telescopes in several frequency bands and may prove to be an even greater obstacle for future generation instruments to overcome. I aim to create a structure of radio astronomy correlators which will be statistically stable (robust) in the presence of interference. A statistical analysis of the mixture of system noise + signal noise + RFI is proposed here which could be incorporated into the block diagram of a correlator. Order and rank statistics are especially useful when calculated in both temporal and frequency domains. Several new algorithms of robust correlators are proposed and investigated here. Computer simulations and processing of real data demonstrate the efficacy of the proposed algorithms