Quiz #5 - Chapter 5 - Standardizing Distributions Flashcards
In a negatively skewed distribution, a student obtains a test score below the mean. What do we know about this student’s z-score?
A: The z-score is negative
B: The z-score is positive
C: The z-score is zero
D: The z-score could be positive or negative
A: The z-score is negative
Researchers are interested in studying factors related to teenage drinking frequency (higher scores = more frequent drinking). In particular, the researchers want to determine whether growing up with an alcoholic parent versus not has an influence on the frequency of drinking. A researcher found a standardized mean difference effect size of -0.9 (non-alcoholic minus alcoholic). How would you characterize the impact of growing up with an alcoholic parent in this study?
A: Growing up with an alcoholic parent had a small positive impact on drinking frequency
B: Growing up with an alcoholic parent had a moderate positive impact on drinking frequency
C: Growing up with an alcoholic parent had almost no impact on drinking frequency
D: Growing up with an alcoholic parent had a large positive impact on drinking frequency
D: Growing up with an alcoholic parent had a large positive impact on drinking frequency
A researcher is summarizing a sample of happiness scores (which are on a scale from 1 to 100). She reports that the sample mean is 60 and the sample standard deviation is 5. If a respondent’s happiness score is 65, what is their corresponding Z score (keep no decimals)?
1
Researchers are interested in the effect of a smoking cessation intervention. Before the intervention, the number of smoked cigarettes per week was recorded for each participant. After the intervention, participants smoked less cigarettes, with a standardized mean difference of -2. Which of the following interpretations is correct?
A: The number of smoked cigarettes decreases by about 2% of a standard deviation unit after the intervention
B: The number of smoked cigarettes decreases by about 2 standard deviations after the intervention
C: The number of smoked cigarettes decreases by 2 cigarettes after the intervention
B: The number of smoked cigarettes decreases by about 2 standard deviations after the intervention
One researcher is interested in the treatment effects of two depression interventions. There are three groups: control group, Intervention A, and Intervention B. Both interventions decreased the depression level scores of participants. Intervention A provides a standardized mean difference of 0.6 (relative to the control), and Intervention B provides a standardized mean difference of 0.5 (relative to the control). Which intervention was most effective at reducing depression symptoms?
A: Intervention B
B: Intervention A
B: Intervention A
A researcher transformed her variable of interest, Depression, to a z-score. She names this z-score variable, Z-Dep. She plots both the Z-Dep and the Depression variables in jamovi. What can she expect from these plots?
A: The shape of the distributions will be different, and you are able to calculate the transformation by using the z-score formula.
B: The shape of the distributions will be different; however, we cannot be sure exactly how the distribution shapes will differ.
C: The shape of the distributions will be the same because z-score transformations do not alter the shape of the original distribution.
C: The shape of the distributions will be the same because z-score transformations do not alter the shape of the original distribution.
A high school math teacher gave their class an exam. The mean grade on the exam was 90 with a standard deviation of 2. The teacher converted the students’ grades to z-scores and then shared these scores with their students. One student got a z-score of -1. What can you say about this student’s grade?
A: This student’s grade was 1 point below the mean grade.
B: This student’s grade was 1 standard deviation above the mean grade.
C: This student’s grade was 1 standard deviation below the mean grade.
D: This student’s grade was 1 point above the mean grade.
C: This student’s grade was 1 standard deviation below the mean grade.
A researcher is interested in the effect of a new teaching method on math performance. Some students are taught with this new method (Intervention group) and some are taught with an older method (Control group). The groups are the same size. Both groups then take an exam. The Intervention group has an average score of 83/100 while the Control group has an average score of 80/100. The average standard deviation across the two groups is 5. How would you describe the groups’ standardized mean difference?
A: Negligible
B: Moderate
C: Large
D: Small
B: Moderate
Use the following table to answer the following two questions.
Jordan: Score = 100 / Mean = 85 / SD = 20
Ben: Score = 100 / Mean = 90 / SD = 5
Egamaria: Score = 100 / Mean = 110 / SD = 20
Han: Score = 100 / Mean = 115 / SD = 5
In the process of selecting a tutor for your statistics class, you have narrowed down your search to four candidates: Han, Ben, Egamaria, and Jordan. Each candidate took a different statistics class and scored 100 points. The mean and standard deviation for each of these classes were different, however. Based on the table above, which candidate should you hire as your tutor? (That is, which candidate would earn the highest standardized score?)
A: Jordan
B: Egamaria
C: Han
D: Ben
D: Ben
Use the following table to answer the following two questions.
Jordan: Score = 100 / Mean = 85 / SD = 20
Ben: Score = 100 / Mean = 90 / SD = 5
Egamaria: Score = 100 / Mean = 110 / SD = 20
Han: Score = 100 / Mean = 115 / SD = 5
And which candidate would be your absolute last resort? (That is, which candidate would earn the lowest standardized score?)
A: Ben
B: Jordan
C: Han
D: Egamaria
C: Han
You have 20 participants’ depression scores, this variable is called Depress. You convert all their scores into z-scores, this variable is called Z-Depress. What is the approximate mean of the Z-Depress variable?
0
You have 20 participants’ depression scores, this variable is called Depress. You convert all their scores into z-scores, this variable is called Z-Depress. What is the approximate standard deviation of the Z-Depress variable?
1
