Hi,

I want to use StandardHypoTestInvDemo.C to calculate upper-limit properly but I find some difference between the result of StandardHypoTestInvDemo.C and the result of original paper of Feldman-Cousins.

The CountingModel is below:

```
using namespace RooFit;
using namespace RooStats;
void CountingModel( int nobs = 3, // number of observed events
double b = 1, // number of background events
double sigmab = 0.01) // relative uncertainty in b
{
RooWorkspace w("w");
// make Poisson model * Gaussian constraint
w.factory("sum:nexp(s[3,0,15],b[1,0,10])");
// Poisson of (n | s+b)
w.factory("Poisson:pdf(nobs[0,50],nexp)");
w.factory("Gaussian:constraint(b0[0,10],b,sigmab[1])");
w.factory("PROD:model(pdf,constraint)");
w.var("b0")->setVal(b);
w.var("b0")->setConstant(true); // needed for being treated as global observables
w.var("sigmab")->setVal(sigmab*b);
ModelConfig mc("ModelConfig",&w);
mc.SetPdf(*w.pdf("model"));
mc.SetParametersOfInterest(*w.var("s"));
mc.SetObservables(*w.var("nobs"));
mc.SetNuisanceParameters(*w.var("b"));
// these are needed for the hypothesis tests
mc.SetSnapshot(*w.var("s"));
mc.SetGlobalObservables(*w.var("b0"));
mc.Print();
// import model in the workspace
w.import(mc);
// make data set with the namber of observed events
RooDataSet data("data","", *w.var("nobs"));
w.var("nobs")->setVal(nobs);
data.add(*w.var("nobs") );
// import data set in workspace and save it in a file
w.import(data);
w.Print();
TString fileName = "CountingModel.root";
// write workspace in the file (recreate file if already existing)
w.writeToFile(fileName, true);
}
```

I give the smaller uncertainty since I want to match the result of Feldman-Cousins paper

Then

I use the command below:

`StandardHypoTestInvDemo("CountingModel.root", "w", "ModelConfig"," " , "data", 0, 2, false, 200, 0, 8, 2000, true)`

The output is below:

```
The computed lower limit is: 0.385632 +/- 0.0317312
The computed upper limit is: 6.00396 +/- 0.104173
Expected upper limits, using the B (alternate) model :
expected limit (median) 2.57069
expected limit (-1 sig) 1.23237
expected limit (+1 sig) 4.5014
expected limit (-2 sig) 0.146673
expected limit (+2 sig) 6.02079
```

does it mean the interval is [ 0.38, 6.00] ?

the plot is