Exercise 17: Understanding Paired or
Dependent Samples t-Test
1. What are the assumptions for conducting a paired or dependent samples t-test in this study?
Which of these assumptions do you think were met by the Lindseth et al. (2014) study?
Distribution of scores are normal or approximately normal, dependent variables are
measured at interval and ration levels, repeated measures data or collected from one group
of subjects resulting in paired scores, differences between the paired scores are different.
In this study I believe the assumptions were met except for #1 the distribution of scores
were not normal
2. In the introduction, Lindseth et al. (2014, p.187) described a “2-week washout between diets”.
What does this mean? Why is this important? The washout time frame would be time to be
cleaned out of the high dose aspartame of the 1st 8 days of the study. This would allow
more accuracy of the 2nd 8-day study results and prevent a biased sample
3. What is the paired t-test 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 paired t-test value for mood (irritability) is 3.4. The result is statistically
significant because p-value is <0.01 per table 2 @ 0.002.
Dependent Samples t-Test
1. What are the assumptions for conducting a paired or dependent samples t-test in this study?
Which of these assumptions do you think were met by the Lindseth et al. (2014) study?
Distribution of scores are normal or approximately normal, dependent variables are
measured at interval and ration levels, repeated measures data or collected from one group
of subjects resulting in paired scores, differences between the paired scores are different.
In this study I believe the assumptions were met except for #1 the distribution of scores
were not normal
2. In the introduction, Lindseth et al. (2014, p.187) described a “2-week washout between diets”.
What does this mean? Why is this important? The washout time frame would be time to be
cleaned out of the high dose aspartame of the 1st 8 days of the study. This would allow
more accuracy of the 2nd 8-day study results and prevent a biased sample
3. What is the paired t-test 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 paired t-test value for mood (irritability) is 3.4. The result is statistically
significant because p-value is <0.01 per table 2 @ 0.002.
