– Who spend more time on the daily commute, Sydney-
siders or Melbournians?
– Statement you regular encounter in the media: such as
“Men earn more money than women”; or “Smoking
shortens smokers’ lives by about 12 years”
11
Sample characteristics vs. population characteristics
•
Sample characteristics
– what you calculate from the
sample, e.g., average satisfaction for HP computer among
male respondents is 1.51
•
Population characteristics
–
The “true” values (e.g., “true” satisfaction for HP computer among
male customers
–
What your RQs are about
–
Unfortunately, the values are
unknown
(and unknowable in this
case)
•
In its essence, the hypothesis testing process is to use
observable relationships between sample characteristics
to
make inference about relationships between
the unknown
population characteristics
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MKF2121
5
Variability
•
Sample characteristics are random variables, e.g., if you
collect data for a few times—e.g., with different samples, or
at different times—you will get different sample averages
•
This variability is an issue that needs to be accounted for
with statistical analysis (in another word, is the difference in
satisfaction we observe in the sample between men and
women real, or just noise?)
•
The first step is to quantity the variability in sample
characteristics in your data (e.g., through metrics such as
variance and standard deviation)
13
How do you really “answer” a research question? The ritualistic
dance of hypothesis testing
1. Problem Definition
2. Clearly State the
Null and Alternative Hypotheses
3. Choose the relevant statistical test
4. Calculate p-value
5. Is p-value<0.05?
No
Do not reject null
Reject null hypothesis
Yes
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1. Problem definition
4/6/2017
15
You have done this already, i.e., your research question
•
Do men and women differ in their satisfaction with
HP computer?
