// using Poisson statistics.
//
// The input is assumed to be binned in @f$(x,y)@f$ as described by
-// the 2D histogram passwd to the Reset member function.
+// the 2D histogram passed to the Reset member function.
//
// The data is grouped in to regions as defined by the parameters
// fXLumping and fYLumping. The total number of cells and number of