{
    using namespace RooFit;
    
    RooRealVar x("x","x",-5.,5.);
    RooRealVar w("w","w", 0.,1.);
    
    RooDataSet data("data","nomial data",RooArgSet(x));
    RooDataSet data_wgt("data_wgt","weighted data",RooArgSet(x,w),"w");
    
    TRandom3 rnd;
    for (int i=0;i<1000;i++) {
        x.setVal(rnd.Gaus(0.,1.));
        data.add(x);
        
        x.setVal(rnd.Uniform(-5.,5.));
        data_wgt.add(x,TMath::Gaus(x.getVal(),0.,1.));
    }
    
    RooRealVar mu("mu","mu",0.,-0.5,+0.5);
    RooRealVar sigma("sigma","sigma",1.,0.8,1.2);
    RooGaussian gaus("gaus","gaus",x,mu,sigma);
    
    TCanvas *c1 = new TCanvas("c1","c1",400,800);
    c1->Divide(1,2);
    
    c1->cd(1);
    gaus.fitTo(data,Minos(true));
    RooPlot* frame1 = x.frame();
    data.plotOn(frame1);
    gaus.plotOn(frame1);
    frame1->Draw();

    c1->cd(2);
    gaus.fitTo(data_wgt,Minos(true));
    RooPlot* frame2 = x.frame();
    data_wgt.plotOn(frame2);
    gaus.plotOn(frame2);
    frame2->Draw();
}