Transcript Probability - University of Central Missouri

Review of Hypothesis Testing
What is Statistical Significance?
What is a Sampling Distribution?
What is the Alpha Level?
What is the Difference Between One-Tailed and Two-Tailed?
What are the Four Outcomes in Hypothesis Testing?
What is Statistical Significance?
A technical decision, not a value judgment
Significant: the Null Hypothesis was
rejected
Not significant: the Null Hypothesis was
not rejected
What is a Sampling
Distribution?
Hypothetical frequency distribution of
sample statistics from an infinite number of
samples.
Allows us to make probability judgments
about the likelihood of obtaining a
particular result.
What is the Alpha Level?
Criterion for how strong the evidence has
to be to reject the Null.
Also called the significance level.
Probability of rejecting Ho when Ho is true
(Type I error).
Set by the researcher.
The conventional alpha level is .05.
What is Difference Between
One-Tailed and Two-Tailed?
One Tailed



Directional hypothesis is tested
One critical value
More powerful
What is Difference Between
One-Tailed and Two-Tailed?
Two Tailed




Non-directional hypothesis is tested
Can also be used with directional hypothesis
Two critical values
Safer
What are The Four Outcomes in
Hypothesis Testing?
Type I Error

Reject Ho when Ho is true
Type II Error

Fail to Reject Ho when Ho is false
Correct Rejection
Correct Failure to Reject
TRUE STATE OF THE WORLD
Ho true
Reject
Ho
Type I error
a
DECISION
Fail to
Reject Ho
Correct
1-a
Ho false
Correct
1-B
(power)
Type II error
B (beta)