Unformatted text preview: mples:
Examples:
– More than 7% of the landings for a certain
More
airline exceed the runway.
airline
– The defective rate on a manufacturing line is
The
less than 10%.
less
– Our percentage of sales outside the United
Our
States is no longer 25%.
States
G. baker, Department of Statistics
G.
University of South Carolina; Slide 21 The Null and Alternative Hypotheses
Null Hypothesis, Ho, represents what we
Null
represents
assume to be true. It is always stated so as
assume to
to specify an exact value of the parameter.
Alternative (Research) Hypothesis, H1
Alternative
or Ha, represents the alternative to the null
represents
hypothesis and allows for the possibility of
several values. It carries the burden of proof.
It
In most situations, the researcher hopes to
disprove or reject the null hypothesis in favor
of the alternative hypothesis.
of
G. baker, Department of Statistics
G.
University of South Carolina; Slide 22 Airline Exceedences
Our research (alternative) hypothesis is that
Our
more than 7% of the landings for a certain
airline exceed the runway.
airline
Let p = proportion exceeding runway H0: p < 0.07
Ha: p > 0.07 (not more than 7%)
more
(more than 7%)
G. baker, Department of Statistics
G.
University of South Carolina; Slide 23 Null and Alternative Hypotheses
We are trying to demonstrate that the
defective rate on a manufacturing line is
less than 10%.
less We want to demonstrate that our
percentage of sales outside the United
States is no longer 25%.
States G. baker, Department of Statistics
G.
University of South Carolina; Slide 24 Steps to a Hypothesis Test
Determine the null and alternative
Determine
hypotheses.
hypotheses.
(2) Collect data and calculate test
Collect
statistic, assuming null hypothesis it
true.
true.
(3) Assuming the null hypothesis is
Assuming
true, calculate the pvalue.
true,
(4) Draw conclusion based on pvalue.
(1) G. baker, Department of Statistics
G.
University of South Carolina; Slide 25 Test Statistic Based on
Test
Normal Dis...
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 Fall '13
 Wang
 Statistics, Normal Distribution, Statistical hypothesis testing, G. Baker

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