Transcript IV. C. Hypothesis Testing

Example
Suppose we want to prove that the mean commute time
for people in Lexington to get to work is less than 20
minutes. A random sample of 125 people yield a sample
mean of 17.8 minutes. Assume the population
standard deviation is 12.9.
 State the hypotheses
 Calculate the test statistic
 Identify the p-value
 Make your decision using 0.01 as the level of
significance
 Interpret the results
Example
Suppose we want to prove that the mean commute time
for people in Lexington to get to work is less than 20
minutes. A random sample of 125 people yield a sample
mean of 17.8 minutes. Assume the population
standard deviation is 12.9.
 How would changing the level of significance to 0.05
affect the hypothesis test?
 How would increasing the sample size affect the
hypothesis test?
 How would a larger population standard deviation
effect the hypothesis test?
Example
A system manager at a large corporation believes more
than 80% of all email received at the corporation is
spam. A simple random of 800 emails received finds
that 688 are spam. Test the managers claim.
 State the hypotheses
 Calculate the test statistic
 Identify the p-value
 Make your decision using 0.05 as the level of
significance
 Interpret the results