August 03, 2019 Saturday
Bedtime Story
Bradford Hill Criteria
Let us quickly go through the list of 9
criteria that Hill had proposed as an epidemiologist as it is something that
can be helpful to all of us in our everyday lives regarding causal relationship
of any agency to any event.
These points essentially boil down to
evidence based medicine or evidence based understanding of reality.
(1) Strength (effect size) – for an
association to be meaningful it is always better to have a greater sample size
than smaller.
(2) Consistency (reproducibility) – for an
association to be credible it must not be single anecdotal experience.
The association should be reproducible by
different people at different places with varying sample sizes.
(3) Specificity – refers to causality that
is limited to a specific population for a specific site and specific disease
where no other likely cause is remaining.
The more specific these factors are the
more likely is the causal association between the theory proposed and the
disease.
(4) Temporality – refers to the sequence of
the events meaning that the effect must necessarily follow the cause and not
the other way around.
(5) Biological gradient – this is an
interesting one and refers to the exposure of the agent.
The idea is that greater the exposure to
the agent greater ought to be its biological response.
This of course is not always true as we
know for instance in a case of anaphylactic reaction wherein the smallest of
the dose can trigger a cascade of events very quickly ending up in severely
exacerbated condition of the organism and even eventual death.
(6) Plausibility – is an interesting term.
Plausibility is based on common knowledge,
our past experiences and the way things generally proceed in similar
situations.
George Pólya, the Hungarian mathematician
(and one among ‘The Martians’) had summed it up this way:
“A mathematical proof is a demonstrative
proof but the inductive evidence of the physicist, the circumstantial evidence
of the lawyer, the documentary evidence of the historian and the statistical
evidence of the economist all belong to the plausible reasoning.”
(7) Coherence – coherence refers to the
correspondence between epidemiological and laboratory findings though a lack of
laboratory evidence does not nullify the epidemiological plausibility.
This is in keeping with the mind that
epidemiological finding could be pointing out to something new previously
unknown to men working in the laboratories.
(8) Experiment – Hill gave experimentation
quite a low priority or perhaps possibility of being executed and wrote
“occasionally it is possible to appeal to experimental evidence.”
Stay tuned to the voice of an
average story storytelling chimpanzee or login at http://panarrans.blogspot.com
Good night Mon Ami and my fellow cousin ape.
Advertisements
Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
No comments:
Post a Comment