“EXERCISE 31 t-test for Dependent Groups”
“Name:” _ ______________________________
“1. What are the two groups whose results are reflected by the t ratios in Tables 2 and 3?”
These are the pre-test and post-test groups, but the same individuals were tested pre-test and posttest.
“2. Which t ratio in Table 2 represents the greatest relative or standardized difference
between the pretest and 3 months outcomes? Is this t ratio statistically significant?
Provide a rationale for your answer.”
t = 4.14 represents the greatest difference between the pretest and 3 month outcome. This is
statistically significant since p < 0.05. It shows there is a significant difference in total risk before
and after the program.
”3. Which t ratio listed in Table 3 represents the smallest relative difference between the
pretest and 3 months? Is this t ratio statistically significant? What does this result mean?”
The smallest relative difference is the Stress Management with a t value of - 0.65. No this is not
statistically significant because the p value is greater than 0.05. The results mean that there is not a
statistically significant difference between stress management between pretest and 3 months,
indicating no change over the time frame. Note: a negative t value does not always indicate the
smallest difference.
“EXERCISE 31 t-test for Dependent Groups”
“4. What are the assumptions for conducting a t-test for dependent groups in a study?
Which of these assumptions do you think were met by this study?”
The assumptions are the scores are approximately normal, dependent variables are measured at
interval or ratio levels, the groups are dependent, and the difference between the paired scores are
independent.
For this study I believe all the assumptions are met except perhaps the last mentioned assumption.
“5. Compare the 3 months and 6 months t ratios for the variable Exercise from Table 3.
What is your conclusion about the long-term effect of the health-promotion intervention
on Exercise in this study?”
The t-scores decrease over time, which shows that in the long term the effects may not be as
significant.
“6. What is the smallest, significant t ratio listed in Table 2? Provide a rationale for your
answer.”
t = -0.80. The absolute value of this t ratio is the smallest, and shows that the effect on BMI over 6
months was minimal or not significant.
“EXERCISE 31 t-test for Dependent Groups”
“7. Why are the larger t ratios more likely to be statistically significant?”
They are more likely to be significant because there is a large difference in the pre and post tested
values, so these are the areas that will be effected most. Their p-values are also smaller.
“8. Did the health-promotion program have a statistically significant effect on Systolic
blood pressure (BP) in this study? Provide a rationale for your answer.”
No, the health-promotion program did not appear to have a significant effect on blood pressure.
This may be because the health program didn’t cover blood pressure, or it was simply something
that people didn’t think about with their overall health.
“9. Examine the means and standard deviations for Systolic BP at pretest, 3 months
(completion of the treatment), and 6 months. What do these results indicate? Are these
results clinically important? Provide a rationale for your answer.”
These results indicate that there was very little change in Systolic BP, as the SD didn’t change at all,
and blood pressure only decreased by a small amount in 3 months, and then shot back up after 6
months. These changes would be considered significant enough to be statistically or clinically
important.
“EXERCISE 31 t-test for Dependent Groups”
“10. Is this study design strong or weak? Provide a rationale for your answer.”
In my opinion, this is a fairly strong study because it identifies what areas the health promotion
program effect the most. It also shows what could be improved in the program. For this reason I
believe the study was fairly effective.
“BONUS QUESTION (Optional)”
“Would you, as a health care provider, implement this intervention at your facility based
on the Total Risk Score results? Provide a rationale for your answer.”
I would implement the areas which I thought were effective and try to improve some of the lower
scoring areas like blood pressure. There is certainly good reason to use many of the aspects of the
health-care program as it was shown to improve total risk score, and health.
“EXERCISE 31 t-test for Dependent Groups”
“Comments for the Instructor:”
“Instructor’s Comments:”
“Score:
“Grading Rubric:”
/ 8:”