{
    using namespace RooFit;
    
    // observables, decay time and its error
    RooRealVar t("t","decay time",0.,10.);
    RooRealVar terr("terr","decay time error",0.001,0.4);
    
    // model for decay time error
    RooRealVar terr_mu("terr_mu","time err mu",0.2);
    RooRealVar terr_sigma("terr_sigma","time err sigma",0.02);
    RooGaussian terr_model("terr_model","time err model",terr,terr_mu,terr_sigma);
    
    // model for decay time (w/ time error in the resolution model)
    RooRealVar tau("tau","Lifetime",1.6,1.2,2.0);
    RooGaussModel res("res","Resolution model",t,RooConst(0.),terr);
    RooDecay t_model("t_model","t_model",t,tau,res,RooDecay::SingleSided);
    
    RooProdPdf model("model","full model",t_model,terr_model);
    RooDataSet* data = model.generate(RooArgSet(t,terr), 10000);
    
    model.fitTo(*data,Minos(true),ConditionalObservables(terr));
    
    RooPlot *frame = t.frame();
    data->plotOn(frame);
    model.plotOn(frame);
    frame->Draw();
}