ACTIVITY - CHANGING PROBABILITIES WHEN NEW INFORMATION IS AVAILABLE
(from DeGroot, 1970)

The point of this activity is to demonstrate that probabilities that we assign are conditional on our current knowledge. As we learn and gain more information, our probabilities about statements can change. Later, we will introduce a formula, Bayes' rule, which will tell us how to compute new probabilities when we get information.

WHEN WAS JOHN TYLER BORN?

  1. Consider the year of birth of John Tyler, former President of the United States. The table below lists four statements about Tyler's year of birth.

    YEAR OF BIRTH PROBABILITY
    no later than 1750
    between 1751 and 1775
    between 1776 and 1800
    after 1800


  2. You are now given the information that John Tyler was the tenth president of the United States. Use this information to reevaluate the probabilities you made above. Before you assign probabilities, answer the first two questions stated above.

Get additional information.
Page Author: Jim Albert (© 1996)
albert@bayes.bgsu.edu
Document: http://www-math.bgsu.edu/~albert/m115/probability/tyler2.html
Last Modified: November 24, 1996