Free Essay: Degrees of Freedom. Assumptions for Conducting a Paired or Dependent Samples T-Test

Exercise 16

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What do degrees of freedom (df) mean? Canbulat et al. (2015) did not provide the dfs 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.

Degrees of freedom constitute the value of figures which are assigned to statistical distributions. Identification of a df for a t ratio is critical in verifying whether t-distribution table data is significant for a given level of significance. df = (88-1) + (88-1) = 174

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 of age for the two groups? Was this an appropriate analysis technique? Provide a rationale for your answer.

The means and standard deviations for the two groups were 8.25 1.51 and 8.61 1.69 respectively. T-test is the statistical analysis used to determine the gap in age means for both groups. The statistical analysis technique was appropriate because it caters for the two sets of data and their means.

What are the t value and p-value for age? What do these results mean?

The age values are -1.498 and 0.136 respectively. Age means for the two categories are not significant.

What are the assumptions for conducting the independent samples t-test?

Random sample, Normal distribution when plotted, measurement of dependent variables is done at ratio or interval scales; Variances are homogenous.

Are the groups in this study independent or dependent? Provide a rationale for your answer.

The two categories are independent. Varied samples were used for individual study. Independent tests were conducted from the control.

What is the null hypothesis for procedural self-reported pain measured with the Wong-Baker Faces Scale (WBFS) for the two groups? Was this null hypothesis accepted or rejected in this study? Provide a rationale for your answer.

There is no difference in self-reported pain WBFS. Given the p-value of < 0.0001 and t value of - 6.498 the hypothesis was rejected.

Should a Bonferroni procedure be conducted in this study? Provide a rationale for your answer.

It is not necessary. It is only mandatory if numerous t-tests are done to decrease Type 1 error risk.

What variable has a result of t = 6.135, p = 0.000? What does the result mean?

The variable with this result is that of the parent-reported index of child nervousness. The data reflects the parents' opinions on the level of their child's stress for the control groups.

In your opinion, is it an expected or unexpected finding that both t values on Table 2 were found to be statistically significant. Provide a rationale for your answer.

It is an expected finding that there was statistical significance in the t values of VAS and WBFS in table 2. Both values are measures of pain.

Describe one potential clinical benefit for pediatric patients to receive the Buzzy intervention that combined cold and vibration during IV insertion.

Buzzy intervention is potentially beneficial because it makes IV insertion less of a disturbing experience for both kids and pediatricians. Most children dread needles, and their anxiety makes IV insertion troublesome.

Exercise 17

What are the assumptions for conducting a paired or dependent samples t-test in a study? Which of these assumptions do you think were met by the Lindseth et al. (2014) study?

The premise included; no significant outliers, normal distribution, two categorical matched pairs for independent variables and measurement of variables on a continuous scale. Assumptions met by the study are; continuous variables, normal distribution and matched pairs of independent variables.

In the introduction, Lindseth et al. (2014) described a "2-week washout between diets." What does this mean? Why is this important?

It shows that the study design is a between-subjects and the examiner made the contributors discontinue for two weeks before shifting groups to "washout" whichever outcome of low or increased content of aspartame in food. This is critical in avoiding puzzling results of having similar cases in two non-identical groups.

What is the paired t-test value for mood (irritability) between the participants' consumption of high- versus low-aspartame diets? Is this result statistically significant? Provide a rationale for your answer.

The t-test value is 3.4. It is of statistical significance because the result exceeds critical value where p value is 0.002 which is below 0.05 alpha level.

State the null hypothesis for mood (irritability) that was tested in this study. Was this hypothesis accepted or rejected? Provide a rationale for your answer.

Aspartame does not have any significant consequence on mood. This hypothesis has been rejected because p=0.002 and t=3.4 indicate that neurobehavioral scores mean values are significantly different.

Which t value in Table 2 represents the greatest relative or standardised difference between the high- and low-aspartame diets? Is this t value statistically significant? Provide a rationale for your answer.

It is the largest t value. Reason being that the t value at 3.8 and p=0.001 < 0.01 makes the result significant with a great relative difference.

Discuss why the larger t values are more likely to be statistically significant.

It is because they show high standard deviations among groups which indicates non-similarity and lack of regular distribution.

Discuss the meaning of the results regarding depression for this study. What is the clinical importance of this result?

The study indicates that participants were profoundly depressed upon consuming a diet rich in aspartame. The clinical importance of this is that the ingredient is available in many foods and mostly in favorite drinks like sodas which could be the primary cause of increased rate of depression.

What is the smallest, paired t-test value in Table 2? Why do you think the lower t values are not statistically significant?

Smallest paired t value is 1.5 for working memory. Statistical significance of small t values is not evident because there is no substantially visible change in different variables under test.

Discuss the clinical importance of these study results about the consumption of aspartame. Document your answer with a relevant source.

According to the study, high rates of depression were registered in the usage of aspartame. The clinical importance of this is that diet can be used to monitor depression. In the study, two participants were diagnosed with cognitive impairment upon consumption of foods rich in aspartame. Depression and memory loss can, therefore, be treated by elimination or regulation of aspartame in diets.

Are these study findings related to the consumption of high- and low-aspartame diets ready for implementation in practice? Provide a rationale for your answer.

No, the findings of the study are not quite ready for practical implementation. The study lacks sufficient data and evidence. Perhaps, extensive sampling and a better-controlled study would give an accurate reflection of the correlation between aspartame and depression.