Science drawing Conclusions:
Autism and vaccines
Who I am.
• I was a researcher at WSU’s Sleep and
Performance Research Center for three years.
• I am a mathematician.
• I am a teacher.
• I am not a doctor or biologist.
Scientific Method
Image courtesy William Harris
Math Stuff
When reading research the most important
number to see is the p-value. This is a loosely
a measure of the likelihood of our hypothesis
being true.
Formally this is the probability of getting a test
statistic at least as extreme as the one
representing sample data (Triola 401).
Examples
Suppose you read that something has a p-value of .0003.
This means the likelihood of the alternate hypothesis being
true is .9997 or 99.97%.
http://www.safeminds.org/research/library/20021107.pdf
More Math Stuff
There is a big difference between correlation
and causation.
Correlation (positive)- As one thing increases
the other increases.
Causation- Since one thing happens then the
other thing happens with greater frequency.
The first is easy to show the second is much
harder.
How to look at Data
• Look at all the Data.
• Listen to the experts. They have been doing
this a while.
• Find out backgrounds of individuals who are
both the experts in their field and the
dissenters.
• Be willing to change your mind if the evidence
suggests or insists you should.
Science can be Wrong
• The P-value essentially measures this
likelihood.
• New results come out and our body of
knowledge grows.
• Science works toward consensus. Through
repeated experimentation.
• Science fixes itself.
• If it flies in the face of the data it is not
science.
Who is creating the data?
• Be wary of who is trying to sell you something.
• http://healthland.time.com/2011/01/06/stud
y-linking-vaccines-to-autism-is-fraudulent/
Scientific Publications
When I published my papers had the form:
• Introduction
• methods
• Results/Conclusions
• References
• Funding
Why should you trust scientific
publications?
• They are peer reviewed.
• If the work is not replicable it is bad for our
careers.
• We disclose who we are paid by.
• If we lie we are usually publicly flogged.
Introduction
• In 1999, concerns were raised that vaccines
containing the preservative Thimerosal™
might increase the risk of autism and/or other
neurodevelopmental disorders.
Methods
• Between the mid-1980s through the late-1990s, we compared the
prevalence/incidence of autism in California, Sweden, and Denmark
with average exposures to Thimerosal containing vaccines. Graphic
ecologic analyses were used to examine population-based data
from the United States (national immunization coverage surveys
and counts of children diagnosed with autism-like disorders seeking
special education services in California); Sweden (national inpatient
data on autism cases, national vaccination coverage levels, and
information on use of all vaccines and vaccine-specific amounts of
Thimerosal); and Denmark (national registry of
inpatient/outpatient-diagnosed autism cases, national vaccination
coverage levels, and information on use of all vaccines and vaccinespecific amounts of Thimerosal).
Results
Source: American Journal of Preventive Medicine 2003; 25:101-106 (DOI:10.1016/S07493797(03)00113-2 )
analysis comparing the average cumulative ethylmercury dose received from vaccines by birth-year cohort from 1981 to 1998, and the
annual number of incident cases of autism in children aged 2 to 10 years diagnosed in Denmark from 1983 to 2000.
Conclusions
The body of existing data, including the
ecologic data presented herein, is not
consistent with the hypothesis that increased
exposure to Thimerosal-containing vaccines is
responsible for the apparent increase in the
rates of autism in young children being
observed worldwide.
References
• Triola, Mario (2010) Elementary Statistics 11th
edition: Boston: Pearson.
• Paul Stehr Green et all (2003). Autism and
Thirmosal caring Vaccines. American Journal of
Preventive Medicine Volume 25, Issue 2 , Pages
101-106.