# Exercise 31

1. What are the two groups whose results are reflected by the t ratios in Tables 2 and 3? The two groups are pre-test and 3-month measures and pre-test and 6-month measures. 2.

**Exercise 31**specifically for you

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. The t ratio for Total risk score represents the greatest relative or standardized difference between the pre-test and 3 months outcomes because the value of t test statistics is bigger than any other group.

This ratio is statistically significant because the p-value corresponding to this group is less than 0. 05. 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 t ratio for Stress management the smallest relative difference between the pre-test and 3 months because the values of t test statistics is smaller than any other group. This ratio is not statistically significant because here the p-value is bigger than 0. 5. This result depicts that there is no significant difference in the stress management at pre-test and after 3 months. Stress management is same at pre-test and at 3 months. 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 for conducting a t-test for dependent groups in a study are the data for both group should be normally distributed and the groups are correlated with each other.

The groups are correlated because the same measurement is taken over from the same subject at pre-test, 3 months and at 6 months. There are 25 subjects in this study and out of 25, 21 have completed the study, it means that the data is enough to conduct the paired sample t test. Also the data should be continuous and this assumption was met because the data is obtained on a interval or ratio scale. 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?

We can see that the magnitude of the score value is larger at 3 months and levels off at 6 months, thus we conclude that over time the long-term health-promotion intervention on Exercise in this study has less of an effect than in the short-term. 6. What is the smallest, significant t ratio listed in Table 2? Provide a rationale for your answer. The smallest significant t ratio is 2. 03 for variable Cholesterol at 3 months. This ratio is significant at 5% level and this is smallest among all other significant t ratios. 7. Why are the larger t ratios more likely to be statistically significant?

The larger t ratios are more likely to be statistically significant because it takes a larger difference between the treatment and comparator with smaller variation. The larger the t ratios the more confident we are about our results. In terms of mathematics, the 99% of the observation for t distribution falls between -3 and +3. So if the t ratio lies outside these values we are more likely to get significant results. 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 do not have a statistically significant effect on Systolic blood pressure (BP) in this study because at both end points such as 3 months and 6 months, the p-values are bigger than 0. 05, so we can conclude that the health-promotion program do not have a statistically significant effect on Systolic blood pressure (BP). 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.

The mean and standard deviation for Systolic BP for pre-test is 121. 7 and 14. 6, for 3 months the means and standard deviations is 117. 2 and 12. 3 and for 6 months the mean and standard deviation is 115. 6 and 13. 4. These results are clinically important because we can see that the mean Systolic BP is decreased after 3 months and after 6 months. The treatment is effective in lowering the Systolic BP as the time passes. In a long run, these results can be significant. 10. Is this study design strong or weak? Provide a rationale for your answer.

The design for this study is strong because the there is only one group and we want to see whether there is any significant difference or reduction in some measurement after receiving the treatment or therapy. This design serves the purpose of the study. The only drawback in this design is that there is no blinding of treatment. Table 2 *p < 0. 05. aPaired t-test results between the pretest and 3-month measures. bPaired t-test results between the pretest and 6-month measures. Table 3 *p < 0. 05. aPaired t-test results between the pretest and 3-month measures. bPaired t-test results between the pretest and 6-month measures.