[ABE-L] Seminários PIPGEs UFSCar/USP

[Michel H. Montoril]

Caros,

Gostaríamos de convidar a todos para o próximo seminário conjunto
UFSCar/ICMC-USP, que ocorrerá no dia *22/07*, *às 14h*. Seguem informações
abaixo.

Sintam-se à vontade para divulgar (arquivo em anexo) entre eventuais
interessados.

Saudações,
Michel

*Scheduled for:*
Jul 22, 2022, at 2:00 pm
(GMT-03:00) Brasilia Standard Time - Sao Paulo

*Video call link HERE <https://meet.google.com/ioi-yrom-smt>.*

*Speaker:*
Nuno Sepúlveda (Warsaw University of Technology)

*Title:*
The three-sigma rule to define antibody positivity: is it a beauty or a
beast?

*Abstract:*
The main objective of many epidemiological studies wanders around the
estimation of the proportion of individuals currently or previously
infected by a given microorganism. Given that an infection inevitably leads
to an immune response, this estimation exercise often requires identifying
individuals who reach a minimal level of microbe-specific antibodies in
their serum. This threshold invariantly follows the three-sigma rule: mean
plus three times the standard deviation from a hypothetical
antibody-negative population. Notwithstanding not being linked to a
specific parametric distribution, it has the most intuitive interpretation
in the context of a normal distribution. I will then discuss the problems
of estimation bias and apparent control of specificity arising from
applying this rule to non-normal distributions for the seronegative
population. I will use public data on antibody testing against the
SARS-CoV2 to illustrate these problems. We should finally ask ourselves
whether the three-sigma rule is a beautiful statistical concept or,
instead, a little beast hidden in antibody data analysis.

*Bio:*
Nuno Sepúlveda has BSc and MSc degrees in Applied Mathematics and
Computation (Statistics) from the Technical University of Lisbon, Portugal.
He developed mathematical theories of the adaptive immune system in his
Ph.D. project in University of Oporto, Portugal. He was a member of the
London School of Hygiene and Tropical Medicine between 2010 and 2019, where
he investigated the genetics and epidemiology of malaria. He got interested
in ME/CFS after collaborating with the CureME group in the statistical
analysis of the United Kingdom ME/CFS biobank. He is the head of the
Immune-Stats group, which has the research mission to find biomarkers of
immunity and disease diagnosis of ME/CFS, Fibromyalgia, long-Covid,
malaria, and other complex diseases. He currently lives in Warsaw with his
wife Anna and his two-year-old son Artur.

===============================
/* Michel H. Montoril,
 * Assistant Professor,
 * Department of Statistics,
 * Federal University of São Carlos,
 * São Carlos, SP, 13565-905, Brazil
 */
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