Hi Wouter, Gerhard, Roel,
On paper 2013-067 I have the following question about weights in a likelihood fit (l.124). See: https://cds.cern.ch/record/1644422?ln=en
They use a global factor to correct (normalise) the weights: alpha = Sum(wi)/Sum(wi^2). They do this to make sure that the error estimates are correct. I know that there can be some caveats with this method, but I am actually wondering what would be a good reference. The paper from Yuehong http://arxiv.org/pdf/0905.0724v1.pdf is not a good reference, because he does not use this normalisation yet (he introduced this later in an internal note). In the paper he only remarks: "Apparently the errors obtained this way using the weighted likelihood function LW are underestimated, because the effect of background fluctuation is not properly accounted for. Reliable error estimates can be obtained from Monte Carlo simulation."
So what is a good reference to suggest to the authors? I am sure that many analyses will have this issue (e.g. B lifetime, DACP).
Cheers Jeroen
On 31 Jan, 2014, at 12:14 pm, Tjeerd Ketel tjeerd@nikhef.nl wrote:
Dear all,
Diego and Maurizio introduced the two papers below this morning and they will collect the comments of us and upload them on CDS before their respective deadlines.
During the discussion of PAPER-2014-001 I found that I had actually read another paper PAPER-2013-067; Jeroen did the same.
Now I should apologize that in fact PAPER-2014-001 was NOT assigned to Nikhef, but that I copy-pasted the wrong email from CERN. I think everybody enjoyed the discussion of that paper and our comments will be usefull.
Nevertheless, we also need to give comments to PAPER-2013-067. I will collect those comments, send them around on Monday and upload them on Wednesday 5 February (its deadline).
Best regards, Tjeerd
On Thu, 30 Jan 2014, Tjeerd Ketel wrote:
Dear colleagues,
Bfys Meeting Friday 31 January at 9:30 in !!! N328 !!! and Vidyo
9:30 - 10:15 Introduction and discussion by Diego of PAPER-2014-003: Precision measurement of the $\Lambda_b^0/\overline{B}^0$ lifetime ratio https://cds.cern.ch/record/1643936
10:15 - 11:00 Introduction and discussion by Maurizio of PAPER-2014-001: Observation of photon polarization in $B^\pm\to K^\pm\pi^\mp\pi^\pm\gamma$ decays https://cds.cern.ch/record/1644210
We succeeded to get N328 and we can continue until 12:00, if needed.
The material can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2799 and will be protected by lhcb, etc.
Vidyo link in Nikhef Bfys Meeting (at Institutes->Nikhef of Friday 21 June 2013) https://indico.cern.ch/conferenceDisplay.py?confId=255991 protected by PIN 1328.
Best regards, Tjeerd
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