code: public static double kurtosis(FlatDataCollection flatDataCollection) {
  	    int n = count(flatDataCollection);
          if(n<=3) {
              throw new IllegalArgumentException("The provided collection must have more than 3 elements.");
          }
          
          double mean = mean(flatDataCollection);
          
          double m4 = moment(flatDataCollection, 4, mean);
          double m2 = moment(flatDataCollection, 2, mean);        
  
          /*
          g2=m4/(m2*m2);
  
          kurtosis=((n-1.0)/((n-2.0)*(n-3.0)))*((n+1.0)*g2 +6.0);
          //kurtosis=g2/(n-1.0)-3.0;
          //kurtosis=g2;
          */
          
          double s = (n/(n-1.0))*m2;
          
          double Mcapital4=n*m4;
          double Mcapital2=n*m2;
          double kurtosis=(n*(n+1.0)*Mcapital4-3*Mcapital2*Mcapital2*(n-1.0))/((n-1.0)*(n-2.0)*(n-3.0)*s*s);
          
          return kurtosis;
      }
docs: Calculates Kurtosis. Uses a formula similar to SPSS as suggested in their documentation (local help)
  
  @param flatDataCollection
  @return