Changeset 75 for trunk/src/ROC.cc

Timestamp:

May 4, 2004, 11:51:58 AM (19 years ago)

Author:

Peter

Message:

fixed bug in get_p_approx

File:

• trunk/src/ROC.cc (modified) (3 diffs)

trunk/src/ROC.cc

@@ -41 +41 @@
         area+=i;
     // Normalizing the area to 0-1
-    area = (2*area/nof_pos_ - nof_pos_ + 1)/(2*value_.size() - 2*nof_pos_);
+    area = (area/nof_pos_ - (nof_pos_ - 1)/2 )/(value_.size() - nof_pos_);
+
     return area;
   }
@@ -51 +52 @@
     if (nof_pos_ < minimum_size_ & value_.size()-nof_pos_ < minimum_size_)
       p = get_p_exact(area*nof_pos_*(value_.size()-nof_pos_), 
-                           nof_pos_, value_.size()-nof_pos_);
+                          nof_pos_, value_.size()-nof_pos_);
     else
     p = get_p_approx(area);
@@ -60 +61 @@
   double ROC::get_p_approx(const double area) 
   {
-    double x = area-0.5;
-    double sigma = ((value_.size()-nof_pos_)*nof_pos_*value_.size()/12/
-                    (2*value_.size() - 2*nof_pos_));
+    double x = area - 0.5;
+    double sigma = (pow((value_.size()-nof_pos_)* nof_pos_ *
+                        (value_.size()+1)/12, 0.5) /
+                    (value_.size() - nof_pos_ ) / nof_pos_);
     double p = gsl_cdf_gaussian_Q(x, sigma);
+        
     return p;
   }