[Olympus] PRC report
Jan C. Bernauer
bernauer at MIT.EDU
Wed Feb 5 17:39:14 EST 2014
Hi Michael,
I would say: If there is any doubt that maybe we would get a result
which steers us into saying "Looks good", we have a bias.
The cross section drops by what, a factor of 10000? so 5% should be good
enough statistics for everything except the last 2 or 3 points.
So I think there is a real danger there.
Best,
Jan
On 2/5/14, 5:33 PM, Michael Kohl wrote:
> Hi,
> I did not mean to include the data/MC plot in the report but to look at
> it myself and for internal discussions.
> As far as blinding is concerned, this plot would be based on the 100
> runs representing only some 5% of the data so is this not blind enough
> for statistical reasons?
>
> Best regards
> Michael
>
>
> On Wed, 5 Feb 2014, Douglas Kenneth Hasell wrote:
>
>> Hi,
>>
>> I agree with Jan. We must not produce anything yet showing
>> data/MC. Showing plots of data and MC in a log scale with arbitrary
>> normalizations are okay but even this is dangerous if the
>> normalizations are the same for electron and positrons.
>>
>> In the future I propose we avoid this problem by actually blinding
>> the data we release to the collaboration.
>>
>> Cheers,
>> Douglas
>>
>> 26-415 M.I.T. Tel: +1 (617) 258-7199
>> 77 Massachusetts Avenue Fax: +1 (617) 258-5440
>> Cambridge, MA 02139, USA E-mail: hasell at mit.edu
>>
>>
>>
>> On Feb 5, 2014, at 12:26 PM, Jan C. Bernauer <bernauer at MIT.EDU> wrote:
>>
>>> Dear all,
>>>
>>> please do NOT do that. We are already dangerously close to produce and
>>> release a "result". To be honest, even the comparison like it is now is
>>> too close for comfort for me. The non-MC corrected yield in a log plot
>>> was the furthest I'm willing to go.
>>>
>>> Dividing the measurement by MC gives almost directly the ratio we are
>>> after - you only have to divide the two numbers in the plot. This most
>>> certainly can not go in the PRC report. And quite frankly, I'm not sure
>>> why we even entertained the thought of blinding the data when we go and
>>> produce results, which will without doubt bias us, the first chance
>>> we get?
>>>
>>> So I'm opposed to producing this plot even for internal use.
>>>
>>>
>>> With best regards,
>>> Jan
>>>
>>>
>>> On 2/5/14, 9:03 AM, Michael Kohl wrote:
>>>> Dear Stan, Yury,
>>>>
>>>> the logarithmic scale is hiding certain features.
>>>> Can you produce a plot of the ratios (data/MC) for e+ and e- ? This
>>>> should
>>>> take out the leading Q2 dependence and help identify the problem zones.
>>>>
>>>> The enhanced e- yield at backward angle was already present in Jan's
>>>> plot
>>>> from October.
>>>>
>>>> Best regards
>>>> Michael
>>>>
>>>>
>>>> On Wed, 5 Feb 2014, Belostotski, Stanislav wrote:
>>>>
>>>>> Dear Douglas and Jan,
>>>>> Find please attached two plots (eps and pdf each)
>>>>> showing comparison experimental yields with MC. The normalization is
>>>>> done as follows:
>>>>> Experimental distributions are normalized one to another under
>>>>> condition
>>>>> that at Q2 around 1 GeV2 the ratio e+/e- must be equal to 1 ( as I
>>>>> understand we used the same philosophy as Jan did) ;
>>>>> The e- MC points are normalized to experiment at Q2=0.65.
>>>>> I avoid to combine both plots in one (too messy). To be honest,
>>>>> they are
>>>>> anyway independent as we have not used normalization to luminosity.
>>>>> To me the results look good enough. The enhancement around Q2=4 for
>>>>> positrons has already been well explained by Jan. I am puzzled by
>>>>> excess
>>>>> of experiment over MC at Q2 larger 1.5 for electrons (somewhat similar
>>>>> but much less pronounced for positrons). Is that bgr contamination?
>>>>> Might be, but it looks rather as a shift by whatever reason.
>>>>> kind regards Stan,Yuri
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>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>
>>>> +---------------------------------------------------------------------
>>>> | Dr. Michael Kohl, Associate Professor and Staff Research Scientist
>>>> | Physics Department, Hampton University, Hampton, VA 23668
>>>> | Jefferson Lab, C117, 12000 Jefferson Avenue, Newport News, VA 23606
>>>> | Phone: +1-757-727-5153 (HU), +1-757-269-7343 (Jlab)
>>>> | Fax: +1-757-728-6910 (HU), +1-757-269-7363 (Jlab)
>>>> | Email: kohlm at jlab.org
>>>> | Cell: +1-757-256-5122 (USA)
>>>> |
>>>> | Deutsches Elektronen-Synchrotron DESY, Bd. 66, Rm. 6,
>>>> | Phone: +49-40-8998-6406, Cell: +49-171-101-1967
>>>> +---------------------------------------------------------------------
>>>> _______________________________________________
>>>> Olympus mailing list
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>>>
>>>
>>> --
>>> Dr. Jan C. Bernauer
>>> Massachusetts Institute of Technology
>>> 77 Massachusetts Ave, Room 26-441
>>> Cambridge, MA, 02139, USA
>>> Phone: (617) 253-6580
>>> _______________________________________________
>>> Olympus mailing list
>>> Olympus at mit.edu
>>> http://mailman.mit.edu/mailman/listinfo/olympus
>>
>>
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>
> +---------------------------------------------------------------------
> | Dr. Michael Kohl, Associate Professor and Staff Research Scientist
> | Physics Department, Hampton University, Hampton, VA 23668
> | Jefferson Lab, C117, 12000 Jefferson Avenue, Newport News, VA 23606
> | Phone: +1-757-727-5153 (HU), +1-757-269-7343 (Jlab)
> | Fax: +1-757-728-6910 (HU), +1-757-269-7363 (Jlab)
> | Email: kohlm at jlab.org
> | Cell: +1-757-256-5122 (USA)
> |
> | Deutsches Elektronen-Synchrotron DESY, Bd. 66, Rm. 6,
> | Phone: +49-40-8998-6406, Cell: +49-171-101-1967
> +---------------------------------------------------------------------
>
--
Dr. Jan C. Bernauer
Massachusetts Institute of Technology
77 Massachusetts Ave, Room 26-441
Cambridge, MA, 02139, USA
Phone: (617) 253-6580
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