{
  gROOT->SetStyle("Plain");
  TRandom3 rndm;
  rndm.SetSeed(123456);  

  TF1 f1("f1", "pol0");
  TH1D chi2("chi2", "Chi2 Prob", 100, 0, 1);
  chi2.SetMinimum(0);
  for (int j = 0; j < 10000; ++j) {
    TH1D h1("h1", "rnd", 10, 0, 1); 
    h1.SetDirectory(0);
    for(int i = 0; i < 1000; ++i) 
      h1.Fill( rndm.Uniform() );
    h1.Fit(&f1, "Q0");
    chi2.Fill(TMath::Prob(f1.GetChisquare(), f1.GetNDF()));
  }
  TCanvas c;
  chi2.Draw();
  c.SaveAs("02-chi2.pdf");
}