diff --git a/src/classes/Makefile.PMusr b/src/classes/Makefile.PMusr
index 85367e73e..35e632b0b 100644
--- a/src/classes/Makefile.PMusr
+++ b/src/classes/Makefile.PMusr
@@ -148,3 +148,5 @@ ifeq ($(OS),LINUX)
 	cp -pv $(SHLIB) $(ROOTSYS)/lib
 	cp -pv $(PMUSRPATH)/*.h $(ROOTSYS)/include
 endif
+
+cleaninstall: clean install
\ No newline at end of file
diff --git a/src/classes/PMusrCanvas.cpp b/src/classes/PMusrCanvas.cpp
index 113131448..6ebbbab75 100644
--- a/src/classes/PMusrCanvas.cpp
+++ b/src/classes/PMusrCanvas.cpp
@@ -49,6 +49,7 @@ ClassImpQ(PMusrCanvas)
 PMusrCanvas::PMusrCanvas()
 {
   fValid = false;
+  fDifferencePlot = false;
   fPlotNumber = -1;
 
   fStyle               = 0;
@@ -166,6 +167,7 @@ void PMusrCanvas::CreateStyle()
 void PMusrCanvas::InitMusrCanvas(const char* title, Int_t wtopx, Int_t wtopy, Int_t ww, Int_t wh)
 {
   fValid = false;
+  fDifferencePlot = false;
 
   fMainCanvas          = 0;
   fTitlePad            = 0;
@@ -1066,4 +1068,19 @@ void PMusrCanvas::HandleDifference()
 {
   cout << endl << ">> will show the difference between the theory and the signal, to be implemented yet. fMainCanvas name = " << fMainCanvas->GetName();
   cout << endl;
+
+  if (fDifferencePlot)
+    fDifferencePlot = kFALSE;
+  else
+    fDifferencePlot = kTRUE;
+
+  // difference plot wished hence feed difference data and plot them 
+  if (fDifferencePlot) {
+    // check if it is necessary to calculate diff data
+    // get current x-range
+  }
+
+  // switch back to the "normal" view
+  if (!fDifferencePlot) {
+  }
 }
diff --git a/src/classes/PRunSingleHisto.cpp b/src/classes/PRunSingleHisto.cpp
index 5c3ff886a..1ab896e41 100644
--- a/src/classes/PRunSingleHisto.cpp
+++ b/src/classes/PRunSingleHisto.cpp
@@ -455,6 +455,19 @@ bool PRunSingleHisto::PrepareFitData()
     }
   }
 
+  // crude estimate of the initial N0 (experimental), the idea is that the integral
+  // over N(t) would be N0 tau if there would be no asymmetry and bkg
+  value = 0.0;
+  for (unsigned i=start; i<runData->fDataBin[histoNo].size(); i++) {
+    value += runData->fDataBin[histoNo][i];
+  }
+  // the factor 0.8 takes into account bkg and asymmetry uncertainties
+  value = value*fTimeResolution/PMUON_LIFETIME*0.8;
+cout << endl << ">> histoNo = " << histoNo << ", NormParamNo = " << fRunInfo->fNormParamNo << ", N0 estimate = " << value;
+  // only update parameter list if fRunInfo->fNormParamNo is a parameter and not a function
+  if (fRunInfo->fNormParamNo < (int)fMsrInfo->GetNoOfParams())
+    fMsrInfo->SetMsrParamValue(fRunInfo->fNormParamNo, value);
+
   // count the number of bins to be fitted
   fNoOfFitBins=0;
   double time;
diff --git a/src/include/PMusrCanvas.h b/src/include/PMusrCanvas.h
index 63ec787dc..3260488f1 100644
--- a/src/include/PMusrCanvas.h
+++ b/src/include/PMusrCanvas.h
@@ -141,6 +141,7 @@ class PMusrCanvas : public TObject, public TQObject
 
   private:
     Bool_t fValid;
+    Bool_t fDifferencePlot; /// flag showing is a difference plot is shown
     Int_t  fPlotNumber;
 
     TStyle    *fStyle;