diff --git a/python/snpSelector.py b/python/snpSelector.py
index 0982e9e33..10d38b303 100755
--- a/python/snpSelector.py
+++ b/python/snpSelector.py
@@ -192,12 +192,15 @@ def fieldRange(variants, field):
     return minValue, maxValue, rangeValue, bins
 
 def printFieldQual( left, right, variants, titv, FPRate, nErrors ):
+    print '  %s nVariants=%8d titv=%.2f FPRate=%.2e Q%d' % (binString(left, right), len(variants), titv, FPRate, phredScale(FPRate))
+
+def binString(left, right):
     leftStr = str(left)
     if type(left) == float: leftStr = "%.2f" % left
     rightStr = "%5s" % str(right)
     if type(right) == float: rightStr = "%.2f" % right
-    #print 'FPRATe', FPRate, phredScale(FPRate)
-    print '  %8s - %8s nVariants=%8d titv=%.2f FPRate=%.2e Q%d' % (leftStr, rightStr, len(variants), titv, FPRate, phredScale(FPRate))
+    return '%8s - %8s' % (leftStr, rightStr)
+    
 #
 #
 #
@@ -226,25 +229,35 @@ def all( p, l ):
         if not p(elt): return False
     return True
 
+def variantBinsForField(variants, field):
+    if not all( lambda x: x.hasField(field), variants):
+        raise Exception('Unknown field ' + field)
+    
+    minValue, maxValue, range, bins = fieldRange(variants, field)
+    print 'Field range', minValue, maxValue, range
+    print 'Partitions', bins
+    return bins
+
+def mapVariantBins(variants, field):
+    bins = variantBinsForField(variants, field)
+    
+    def variantsInBin(bin):
+        left, right = bin[0:2] 
+        def select( variant ): return variant.getField(field) >= left and (right == '*' or variant.getField(field) <= right)
+        return left, right, selectVariants(variants, select)
+        
+    return imap( variantsInBin, bins )
+
 def calibrateFeatures(variants, fields, titvTarget, updateCalls = True, printCall = False):
     if updateCalls: recalCalls = dict([[variant, RecalibratedCall(variant, fields)] for variant in variants]) 
     
     for field in fields:
         print 'Optimizing field', field
         
-        if not all( lambda x: x.hasField(field), variants):
-            raise Exception('Unknown field ' + field)
-        
-        minValue, maxValue, range, bins = fieldRange(variants, field)
-        print 'Field range', minValue, maxValue, range
-        print 'Partitions', bins
         titv, FPRate, nErrors = titvFPRateEstimate(variants, titvTarget)
         print 'Overall FRRate:', FPRate, nErrors, phredScale(FPRate)
-        
-        for left, right in map(lambda x: [x[0], x[1]], bins): 
-            #print 'LR:', left, right
-            def select( variant ): return variant.getField(field) >= left and (right == '*' or variant.getField(field) <= right)
-            selectedVariants = selectVariants(variants, select)
+
+        for left, right, selectedVariants in mapVariantBins(variants, field):
             if len(selectedVariants) > max(OPTIONS.minVariantsPerBin,1):
                 titv, FPRate, nErrors = titvFPRateEstimate(selectedVariants, titvTarget)
                 if updateCalls: 
@@ -261,6 +274,40 @@ def calibrateFeatures(variants, fields, titvTarget, updateCalls = True, printCal
     else:
         return None
 
+class CallCmp:
+    def __init__(self, nTP, nFP, nFN):
+        self.nTP = nTP
+        self.nFP = nFP
+        self.nFN = nFN
+    
+    def FPRate(self):
+        return (1.0*self.nFP) / max(self.nTP + self.nFP, 1)
+    
+    def __str__(self):
+        return 'TP=%6d FP=%6d FPRate=%.2f FN=%6d' % (self.nTP, self.nFP, self.FPRate(), self.nFN)
+
+def variantInTruth(variant, truth):
+    return variant.getLoc() in truth
+
+def sensitivitySpecificity(variants, truth):
+    nTP, nFP = 0, 0    
+    for variant in variants:
+        if variantInTruth(variant, truth):
+            nTP += 1
+        else:
+            if OPTIONS.printFP: print 'FP:', variant
+            nFP += 1
+    nFN = len(truth) - nTP
+    return CallCmp(nTP, nFP, nFN)
+
+
+def compareCalls(optimizedCalls, truthCalls):
+    for left, right, selectedVariants in mapVariantBins(optimizedCalls, 'QUAL'):
+        callComparison = sensitivitySpecificity(selectedVariants, truthCalls)
+        print binString(left, right), 'titv=%.2f' % titv(selectedVariants)[0], callComparison
+    
+
+
 def main():
     global OPTIONS
     usage = "usage: %prog files.list [options]"
@@ -272,7 +319,7 @@ def main():
                         type='string', default=None,
                         help="VCF formated truth file")
     parser.add_option("-p", "--partitions", dest="partitions",
-                        type='int', default=10,
+                        type='int', default=25,
                         help="Number of partitions to examine")
     parser.add_option("-s", "--s", dest="skip",
                         type='int', default=1,
@@ -286,9 +333,12 @@ def main():
     parser.add_option("", "--titv", dest="titvTarget",
                         type='float', default=None,
                         help="If provided, we will optimize calls to the targeted ti/tv rather than that calculated from known calls")
-                        
+    parser.add_option("", "--fp", dest="printFP",
+                       action='store_true', default=False,
+                        help="")
+         
     (OPTIONS, args) = parser.parse_args()
-    if len(args) != 2:
+    if len(args) > 2:
         parser.error("incorrect number of arguments")
 
     fields = OPTIONS.fields.split(',')
@@ -301,7 +351,13 @@ def main():
     print 'Ti/Tv known', titv(selectVariants(calls, VCFRecord.isKnown))
     print 'Ti/Tv novel', titv(selectVariants(calls, VCFRecord.isNovel))
 
-    optimizeCalls(calls, OPTIONS.fields.split(","), OPTIONS.titvTarget)
+    optimizedCalls = optimizeCalls(calls, OPTIONS.fields.split(","), OPTIONS.titvTarget)
+
+    if len(args) > 1:
+        truthFile = args[1]
+        print 'Reading truth file', truthFile
+        truth = dict( [[v.getLoc(), v] for v in readVariants(truthFile)])
+        compareCalls(optimizedCalls, truth)
 
 if __name__ == "__main__":
     main()
\ No newline at end of file
diff --git a/python/vcfReader.py b/python/vcfReader.py
index c8b8ec8e5..a806025a8 100755
--- a/python/vcfReader.py
+++ b/python/vcfReader.py
@@ -31,6 +31,7 @@ class VCFRecord:
     
     def getChrom(self): return self.get("CHROM")
     def getPos(self): return self.get("POS")
+    def getLoc(self): return str(self.getChrom()) + ':' + str(self.getPos())
 
     def getID(self): return self.get("ID")
     def isNovel(self): return self.getID() == "."