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 assumptions for conducting such test are the following: the evaluation of variables on a continuous scale; a complex independent variable including two categorical matched pairs; the absence of meaningful outliers; the common distribution. The research under consideration corresponds these demands, such as continuity of the variables, matching pairs of the independent variables, and the common distribution.
In the introduction, Lindseth et al. (2014) described a “2-week washout between diets.” What does this mean? Why is this important?
The issue of two-week washout means that the research follows a between-subjects design, and the researcher planned a pause of two weeks for participants before turning groups to “washout.” This step protects the research from the repetition of the same subjects in different experimental 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?
The irritability t-test value is 3.4. This result has a statistical meaning because the t-test value is higher than the critical, and the p = 0.002, which is considerably lower than the alpha level of 0.05.
What was the null hypothesis for mood (irritability) tested in this study? Was this hypothesis accepted or rejected?
The null hypothesis stated that aspartame did not influence the mood. This hypothesis was denied. The p value is 0.002, and t-test statistic is 3.4. These values mean that the average values of their neurobehavioral scores vary substantially.
Which t value in Table 2 represents the greatest relative or standardized difference between the high- and low-aspartame diets? Is this t value statistically significant?
The greatest relative difference between high- and low-aspartame diets is represented by t value. The t-value has statistical meaning at 3.8, with a p of 0.001. The meaningfulness of the result is supported by the p value which is lower that the alpha level of 0.05.
Why are the larger t values more likely to be statistically significant?
The t value assesses the size of the difference corresponding the variation in the sample population. Consequently, the diversity between sample populations will increase with the growth of the t value.
What is the clinical importance of this result regarding depression for this study?
The research proves that a high aspartame diet decreases depression. This fat has a clinical meaning since aspartame is a usual component in diet sodas. This could serve as explanation to some people’s depressions.
What is the smallest, paired t -test value in Table 2? Why are the smaller t values not statistically significant?
The smallest t-value is 1.5. It assesses the working memory. It means that the difference between groups as compared to the diversity in the sample does not have a statistical meaning.
What is the clinical importance of these study results about the consumption of aspartame?
The results of the investigation are clinically important because aspartame prevails in the diets of numerous individuals. Apart from neurobehavioral effects, this substance should be investigated in relation to other side-effects. Aspartame should be avoided by people with phenylketonuria. Besides, it can precondition dyskinesia, diabetes, and even cancer.
Are these study findings related to the consumption of high- and low-aspartame diets ready for implementation in practice?
The research results cannot be immediately implemented into practice. Although the evidence is promising, the studies with a stricter control are needed. Probably a bigger sample will provide the reliability of the results.
Reference
Lindseth, G. N., Coolahan, S. E., Petros, T. V., & Lindseth, P. D. (2014). Neurobehavioral Effects of Aspartame Consumption. Research in Nursing & Health, 37(3), 185–193.