Generally, I think it is
safe to say that most people are introduced to statistical inference from a
frequentist perspective. Many students in graduate programs in statistics
are not taught the basics of the Bayesian paradigm including subjective
probability, the modeling of prior beliefs through probability
distributions, and posterior and predictive inference. This lack of
exposure of students to Bayesian thinking has had a major impact on the
growth of the use of Bayesian methods in areas of application. I think it
is important to discuss how we can effectively communicate Bayesian ideas
in academic and industrial settings and how we can facilitate the spread of
Bayesian thinking among applied statisticians.
This column will discuss a variety of issues relevant to teaching Bayesian
ideas. Here is a short list of some topics, although other suggestions by
ISBA members are certainly welcome.
How can one introduce Bayesian thinking in the standard elementary
statistics class taught as a service course to non-math majors?
Is it desirable to teach both Bayesian and frequentist thinking in an
introductory class?
What topics should be taught in an introductory applied Bayesian course at
the graduate level?
What is the role of software in teaching Bayesian inference?
What are effective short courses for teaching Bayesian methodology?
How do we argue that Bayesian inference is superior (at least in some
settings) to frequentist inference?
In future columns, I hope to describe Bayesian courses that are currently
offered and give reviews of recently published texts and software that will
help in communicating Bayes.
Recently (August 1997) a series of articles appeared in the American
Statistician on the desirability of introducing Bayesian thinking in the
first introductory statistics class taught as a service course to students
outside of the mathematics or statistics department. I have taught
introductory statistics for over 20 years and I have found it very
difficult communicating frequentist thinking to this audience. The notion
of a sampling distribution is obscure to students and, more importantly,
the students have a hard time understanding the repeated sampling
interpretation of confidence. I think Bayesian thinking is very attractive
at this level. Thinking in terms of subjective probability is very natural
for students and Bayes rule can be taught as a formal mechanism for the
natural process of updating one's beliefs about unknowns when more
information is observed.
Currently Alan Rossman and I are writing a beginning statistics text that
introduces inference from a Bayesian viewpoint. The first half of the test
focuses on data analysis. The second half introduces probability basics
-- the focus is on the interpretation of discrete probability tables for
one and two variables. Inference is first introduced for categorical
models using Bayes rule. A two-way table, a ``Bayes box" (hypothetical
counts classified by models and data), is used to teach Bayes rule. We
then have chapters on inference for one and two proportions and a normal
mean. We focus on the use of discrete priors for unobservables, since
these are easier to assess and interpret and it avoids any use of calculus.
One innovative aspect of this text is that it essentially is a collection
of activities that students work on in class in small groups. Currently
we are using this material at Bowling Green for five sections a semester.
I think the course is successful in getting across the big ideas in
inference (population, samples, confidence in making inference) and the
student is well prepared to take a second statistics class on methodology.
Unfortunately, there are very few elementary statistics texts currently
available that use Bayesian thinking. One text of note is Don Berry's
text ``Statistics: A Bayesian Perspective". I have used Don's text both at
Duke and Bowling Green with success and I would recommend it for anyone who
is teaching a one semester introductory class. Don's text has been very
influential in my thinking about teaching elementary Bayes.
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