Chapter 22 (Student)
1
What Is A Test of Significance?
• Inferential Technique: Hypothesis Testing (Test of Significance)
• We want to test a hypothesis (statement) about the value of a
parameter based on sample data.
• Statistical Hypotheses
are statements about population
parameters.
• Example: The proportion of all USC students from South
Carolina is greater than 0.71.
Hypothesis Testing
• In statistics, we test one hypothesis against another.
• Null Hypothesis
, H
0
: The claim being tested in a statistical
test. Usually a statement of “no effect” or “no difference.”
– The null hypothesis is assumed true during the test.
• Alternative Hypothesis
, H
a
: The claim we hope or suspect is
true.
The claim we want to prove.
Hypothesis Testing
• We conduct a hypothesis test under the assumption that H
0
is
true and the claim we believe, H
a
, is not true.
• The test is designed to assess the strength of the evidence
against H
0
.
•H
0
and H
a
are statements about the population and are stated in
terms of a population parameter.
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View Full DocumentChapter 22 (Student)
2
Hypothesis Testing
• The null hypothesis is usually stated so as to specify an exact
value of the parameter (“no effect” or “no difference”).
H
0
: p = c
• The alternative hypothesis allows for the possibility of several
values.
– Onesided alternative
H
a
: p < c
or
H
a
: p > c
– Twosided alternative
H
a
: p
≠
c
(where c is some real value)
Example
• We believe that the true proportion of all USC students from
South Carolina is greater than 0.71.
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 Fall '07
 JOHNSON
 Statistics, Null hypothesis, Statistical hypothesis testing, Statistical significance, H0. · H0

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