In: Statistics and Probability
A sample obese adult males were randomly divided into two groups
in a clinical program. In the experimental group, participants were
involved in a vigorous 30-minute-per-day exercise program and also
given instructions on the importance of diet. The control group
only received the diet instructions. The program directors want to
determine if the exercise program had an impact on LDL cholesterol
levels. Below are the LDL cholesterol data after one month in the
program. What can be concluded with an α of
0.05?
control | exprt |
129 127 131 126 127 129 128 148 125 129 |
132 130 135 131 132 128 137 131 132 132 |
a) What is the appropriate test statistic?
---Select---naz-testOne-Sample t-testIndependent-Samples
t-testRelated-Samples t-test
b)
Condition 1:
---Select---obese adult malesexprt groupLDL cholesterolone
monthcontrol group
Condition 2:
---Select---obese adult malesexprt groupLDL cholesterolone
monthcontrol group
c) Input the appropriate value(s) to make a
decision about H0.
(Hint: Make sure to write down the null and alternative hypotheses
to help solve the problem.)
p-value =______ ; Decision: ---Select---Reject H0Fail to
reject H0
d) Using the SPSS results,
compute the corresponding effect size(s) and indicate
magnitude(s).
If not appropriate, input and/or select "na" below.
d = _______ ;---Select---natrivial effectsmall
effectmedium effectlarge effect
r2 =________ ; ---Select---natrivial
effectsmall effectmedium effectlarge effect
e) Make an interpretation based on the
results.
Participants that exercised with diet instructions had significantly reduced LDL cholesterol levels.
Participants that exercised with diet instructions had significantly increased LDL cholesterol levels.
There is no significant LDL cholesterol difference between the groups.
a)
Independent-Samples t-test
................
Ho : µ1 - µ2 = 0
Ha : µ1-µ2 ╪ 0
Level of Significance , α =
0.05
Sample #1 ----> sample 1
mean of sample 1, x̅1= 129.90
standard deviation of sample 1, s1 =
6.59
size of sample 1, n1= 10
Sample #2 ----> sample 2
mean of sample 2, x̅2= 132.00
standard deviation of sample 2, s2 =
2.49
size of sample 2, n2= 10
difference in sample means = x̅1-x̅2 =
129.9000 - 132.0 =
-2.10
pooled std dev , Sp= √([(n1 - 1)s1² + (n2 -
1)s2²]/(n1+n2-2)) = 4.9827
std error , SE = Sp*√(1/n1+1/n2) =
2.2284
t-statistic = ((x̅1-x̅2)-µd)/SE = (
-2.1000 - 0 ) /
2.23 = -0.942
Degree of freedom, DF= n1+n2-2 =
18
p-value = 0.358465
(excel function: =T.DIST.2T(t stat,df) )
Conclusion: p-value>α , Do not reject null
hypothesis
.................
effect size,
cohen's d = |( x̅1-x̅2 )/Sp | = 0.421
medium effect
...............
There is no significant LDL cholesterol difference between the groups.
...............
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