Signal Significance in the Presence of Systematic and Statistical   Uncertainties
  The incorporation of uncertainties to calculations of signal significance in planned experiments is an actual task. Several approaches to this problem are discussed. We present a procedure for taking into account the systematic uncertainty related to nonexact knowledge of signal and background cross sections. A method of a treatment of statistical errors of the expected signal and background rates is proposed. The interrelation between Gamma- and Poisson distributions is demonstrated. 
S.I. Bityukov (IHEP, Protvino)