Transcript Some Hypotheses Tests

Some Hypotheses Tests
Examples of testing the mean and the
proportion with single samples
P-value method
In the 1980’s it was generally believed that autism affected about 8% of the
nation’s children. Some people believe that the increase in the
number of chemicals in the environment has led to an increase in
the incidence of autism. A recent study examined 384 children and
found that 46 of them showed signs of some form of autism. Is
there strong evidence that the level of autism has increased at the
5% significance level?
H 0 : p  .08
H A : p  .08
Using the calculator
• Stat…tests…(5)1-PropZ-test..enter
• Use the p value to help make the
decision.
Decision and conclusion
• Decision: Reject the null hypothesis
• Conclusion: There has been an increase
in the number of children with autism.
The heart rate of a healthy lion is approximately normally distributed with a
mean of 40 beats per minute. A heart rate that is too slow or too fast can
indicate a health problem. A vet has observed the following beats of a young
lion's heart who is recovering from surgery. Do these data indicate that the
lion may have a health problem?
30
37
43
38
35
36
H 0 :   40
H A :   40
Use the calculator
• Stat…edit- enter the data
30
37
43
38
35
• Stat…tests…T-test..
36
Use the p-value to help you decide
Decide and conclude
• Decision- do not reject the null
hypothesis
• Conclusion- The lion probably does not
have a heart condition since the data
show his heart beat is close enough to
40 beats.
A manufacturer claims that the average life span of its washing machines is
at least 4 years. It is assumed that the distribution of the life spans is
approximately normal. A random sample of 32 of these machines had
an average life span of 3.6 years and a standard deviation of 1.5
years. Is there statistical evidence to dispute the manufacturer's
claim?
H0 :   4
HA :   4
Use the calculator
• Stat…tests…T-test
Use the p-value to help you decide
Decide and conclude
• Decision- fail to reject the null
hypothesis
• Conclusion- the manufacturer is correct
in his claim
Now, you try some!