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https://indico.cern.ch/event/769726/
DAY-1, 31.07.2019
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0930-1050: Glen Cowan, Louis Lyons
Session: Preamble and Intro to Statistics
Convener: Jan Conrad
“Introductory Statistics Talks”
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Wednesday, 31. July 2019 |
Video-Recording for any system with MP4-support
- Video1.mp4 (ca.296 Mb) |
09:30 – 10:20 |
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Time: |
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Wednesday, 31. July 2019 |
Video-Recording for any system with MP4-support
- Video2.mp4 (ca.275 Mb) |
10:25 – 11:15 |
Description:
These will review
some simple statistical concepts that are relevant to this Workshop.
Among other
topics, it will include upper limits, p-values and likelihood ratios.
It is intended
for those who would like to be reminded of their Statistics,
before the
Workshop begins.
Glen Cowan
Louis Lyons (Imperial College (GB))
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- 1510-1540: Sara Algeri.
Session: Blind Analysis, Look Elsewhere
"Correcting for the look-elsewhere
effect: why, when and how"
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Wednesday, 31. July 2019 |
Video-Recording for any system with MP4-support
- Video3.mp4 (ca.167 Mb) |
15:30 – 16:00 |
Description:
The
look-elsewhere effect is a phenomenon which often arises when looking for
signals
whose location is
not known in advance. In this setting, signal searches can be conducted
by performing
several tests of hypothesis at different positions over the search area
considered.
However, if the result of each individual test is not adequately adjusted for
the
fact that many
tests are conducted simultaneously, the overall probability of false
discoveries
rapidly increases with the number of tests. Alternatively, one can consider the
unknown position
of the signal as a nuisance parameter and construct confidence intervals
and statistical
tests of hypothesis by means of Monte Carlo simulations or methods relying
on random fields
and extreme value theory. The goal of this talk is to provide an overview
of the most
common methods used to correct for the look-elsewhere effect and highlight
their advantages
and limitations with respect to the goal of the experiment and the conditions
under which the
statistical analysis is performed.
Dr. Sara Algeri
(University of Minnesota)
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DAY-2, 01.08.2019
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0900-09.30 Alessandra Brazzale
Session: Limit Setting Methods
Convener: Tarek Saab
"Likelihood asymptotics and
beyond"
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Time: |
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Thursday, 01. Aug. 2019 |
Video-Recording for any system with MP4-support
- Video1.mp4 (ca.209 Mb) |
09:00 – 09:30 |
Description:
I will review
some classical methods of asymptotic inference and their higher order
extensions. The focus
will be on modern likelihood based solutions, though Bayesian
counterparts will
be mentioned in by-passing. The discussion will touch upon topics
such as small
sample sizes, large number of nuisance parameters, nonregular settings
and complex
models.
Alessandra Brazzale
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11:00-1135 Sara Algeri
Session: Signal and Backgrounds
"Detecting new
signals under background mismodelling"
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Thursday, 01. Aug. 2019 |
Video-Recording for any system with MP4-support
- Video2.mp4 (ca.184 Mb) |
11:00 – 11:35 |
Description:
When searching
for new astrophysical phenomena, uncertainty arising from background
mismodelling can
dramatically compromise the sensitivity of the experiment under study.
Specifically, overestimating
the background distribution in the signal region increases the
chances of
missing new physics. Conversely, underestimating the background outside
the signal region
leads to an artificially enhanced sensitivity and a higher likelihood of
claiming false
discoveries. The aim of this work is to provide a unified statistical algorithm
to perform
modelling, estimation, inference and signal characterization under background
mismodelling. The
method proposed allows to incorporate the (partial) scientific knowledge
available on the
background distribution, and provides a data-updated version of it in a
purely
nonparametric fashion, without requiring the specification of prior
distributions.
If a calibration
sample or control regions are available, the solution discussed does not
require the
specification of a model for the signal; however, if the signal distribution is
known,
it allows to
further improve the accuracy of the analysis and to detect additional signals
of unexpected new
sources.
Dr. Sara Algeri (University of Minnesota)
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DAY-3, 02.08.2019
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1330-1400: Robert Cousins
Presenters: : Robert Cousins Jr;
Robert Cousins Jr;
Robert Dacey Cousins Jr
"Reflections on 20+ years of
Feldman-Cousins: Hypothesis testing of a point null
vs
a continuous alternative"
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Friday, 02. Aug. 2019 |
Video-Recording for any system with MP4-support
- Video1.mp4 (ca.246 Mb) |
13:30 – 14:20 |
Description:
I will discuss aspects
of the frequentist and Bayesian approaches
to testing a
point null hypothesis (say mu=0) versus a continuous
alternative
hypothesis (say mu>0). This test arises frequently
in particle
physics (including dark matter searches), where
mu is the signal
strength. The frequentist testing approach
maps identically
onto the frequentist theory of confidence
intervals. Thus,
as Feldman and Cousins eventually realized,
the method
advocated in their 1998 paper on confidence intervals
maps identically
onto the "classical" theory of hypothesis
testing in
Kendall and Stuart (which in addition includes
nuisance
parameters). Meanwhile, the traditional Bayesian
approach to
hypothesis testing (due to Jeffreys) is completely
separate from the
Bayesian approach to credible intervals, with
no corresponding
mapping. Direct sensitivity to the prior pdf
for mu, even in
the asymptotic limit of large sample size,
is a consequence,
as is the Jeffreys-Lindley paradox
(arXiv:1310.3791).
My talk will draw
on parts of my “Lectures on Statistics in
Theory: Prelude
to Statistics in Practice” arXiv:1807.05996.
Robert Cousins Jr (University of
California Los Angeles (US))
Robert Cousins Jr (University of
California Los Angeles (US))
Robert Dacey Cousins Jr (Univ. of
California Los Angeles (UCLA))
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Session: White Paper/Discussion 3
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1540-1640: Brazzale, Lippincott
Session:
Optional: White Paper 2
"Statisticians summary"
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Friday, 02. Aug. 2019 |
Video-Recording for any system with MP4-support
- Video2.mp4 (ca.183 Mb) |
15:30 – 16:10 |
Description:
Statisticians summary
Primary author: Alessandra Brazzale
"Physicists Summary"
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Friday, 02. Aug. 2019 |
Video-Recording for any system with MP4-support
- Video3.mp4 (ca.130 Mb) |
16:10 – 16:40 |
Description:
Physicists
Summary
Hugh Lippincott (Fermilab)
Primary author: Jan Conrad