boolean pass = false;
        try {
            Statistics.calculateMean((Collection) null);
        }
        catch (IllegalArgumentException e) {
            pass = true;
        }
        assertTrue(pass);

        pass = false;
        try {
            Statistics.calculateMean((Collection) null, false);
        }
        catch (IllegalArgumentException e) {
            pass = true;
        }
        assertTrue(pass);