Statistics Exercise 16 and 17

Statistics
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22nd August 2018
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Exercise 16
1. What do degrees of freedom (df ) mean? Canbulat et al. (2015) did not provide the df s in
their study. Why is it important to know the df for a t ratio? Using the df formula,
calculate the df for this study.
Answer
Degrees of freedom (df ) refers to the number of values that are normally assigned to
statistics distribution. It is crucial to know the df for a t-ratio so as to determine if the data
in a t-distribution table is significant or not at a certain level of significance.
The df for this study is:
df =(88+88)−2=174
2. What are the means and standard deviations (SDs) for age for the Buzzy intervention and
control groups? What statistical analysis is conducted to determine the difference in means
for age for the two groups? Was this an appropriate analysis technique? Provide a
rationale for your answer.
Answer
Group Mean Standard deviation
(SD)
Buzzy group 8.25 1.51
Control Group 8.61 1.69
The statistical test used was the independent samples t-test. The test was ideal since there
were only two groups to be compared.
3. What are the t value and p value for age? What do these results mean?
Answer
T-value -1.498
P-value 0.136
The results clearly shows that the differences in the means for the two groups (buzzy and
control) are insignificant at 5% level of significance.
4. What are the assumptions for conducting the independent samples t-test?
Answer
The assumptions are as follows:
a. Normal distribution of the datasets.
b. Dependent variable measured on ratio or interval level.
c. Homogeneity of variance in the two groups, that is, the two groups need to have
equal variance.
d. The groups should be independent of each other.
5. Are the groups in this study independent or dependent? Provide a rationale for your
answer.
Answer
The two groups are independent of each other. The groups are independent since a subject
being in buzzy group is not related at all with being in the control group.
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