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Lecture 5

PSYC 210 Lecture Notes - Lecture 5: Test Statistic, Decision Rule, Sampling Distribution


Department
Psychology
Course Code
PSYC 210
Professor
Snjezana Huerta
Lecture
5

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Ѱ 210 Hypothesis Test Examples dependent t test
(matched)
Snjezana.Huerta@sfu.ca
Does the level of physical activity during adolescence (i.e., as measured by the number of hours
of physical activity per week between 13 and 19 years of age) differ significantly amongst
sibling dyads with a 10-year gap between their ages? Assume a willingness to reject a true null
5% of the time, that the variable of interest is normally distributed in the parent population, and
that we have randomly selected five sets of siblings who meet this criterion.
Step 1: Specify the Parent Population
D ~
where D is the Difference score, calculated as ______________
Scale of measurement: ____________
Assumptions to be tested:
Normality of the distribution of the Difference scores
Step 2: Specify hypotheses.
H
0
:
H
1
:
Step 3: Specify the test statistic and the null distribution.
D
s
cD
t
=)(
0
µ
~
t
(n-1)
where
n
= the number of sibling dyads
(
)
===Ε
D
youngerolder
D
µµµ
-
n
=
n
s
s
D
D
2
=
calculated after collect data
Step 4: Specify decision rule(s).
α
= _____; ____-tailed test;
df
= ________;
critical value(s): ________________________
*Collect data
(using random sampling)
& conduct thorough descriptive analyses
, including...
Pair
O
i
Y
i
D
i
1
6 4
2
4 3
3
7 5
4
8 2
5
3 7
Sum:
Step 5: Calculate the observed value of the test statistic.
Calculate the estimated standard error for the sampling distribution:
Calculate the test statistic:
D
obs
s
cD
t
=
0
µ
Step 6: Make a decision re: H
0
.
t
obs
t
crit
n
D
n
i
i
D
=
=1
2
)( DD
i
)( DD
i
1
)(
1
2
=
=
n
DD
D
n
ii
s
D
µ
n
s
s
D
D
=
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