# The Precise Meaning of the Probability Value (2 of 3)

To illustrate that the probability is not the probability of the
hypothesis, consider a test of a person who claims to be able to
predict whether a coin will come up heads or tails. One should take a
rather skeptical attitude toward this claim and require strong
evidence to believe in its validity. The null hypothesis is that the
person can predict correctly half the time (H

_{0}: π = 0.5). In the
test, a coin is flipped 20 times and the person is correct 11 times.
If the person has no special ability (H

_{0} is true), then
the probability of being correct 11 or more times out of 20 is 0.41.
Would someone who was originally skeptical now believe that there is
only a 0.41 chance that the null hypothesis is true? They almost
certainly would not since they probably originally thought
H

_{0} had a very high probability of being true (perhaps as
high as 0.9999). There is no logical reason for them to decrease their
belief in the validity of the null hypothesis since the outcome was
perfectly consistent with the null hypothesis.