# Expert Answers

(For questions 1 – 5): There are many variables in Stat_Grades.sav that can be used to describe the students in the dataset. Use the variable Ethnicity and answer the following questions:

1. Using the Variable View in SPSS (lower left), write out how Ethnicity is labeled, and note how many Ethnicity categories are included.

2. What type of data and level of measurement does the Ethnicity variable represent: Is the data discrete or continuous? Is the data qualitative or quantitative? Is the data nominal, ordinal, ratio, or interval?

3. Use SPSS to output the mean, median, and mode for the Ethnicity. Include the SPSS here. Which of the three descriptive numerical measures of central tendency (mean, median, or mode) BEST describes the variable Ethnicity? What information does the measure tell you about the students in the dataset (Stat_Grades.sav) – be specific?

4. Which of the three descriptive numerical measures of central tendency (mean, median, or mode) LEAST (or most poorly) describes the variable Ethnicity? Explain.

5. Choose the most appropriate graph to represent the variable Ethnicity. (There is more than one possible answer). Create the graph in SPSS and include it here. Be sure the graph is fully labeled. Does this graph confirm what the mode tells you about this dataset? Explain.

6. What type of data and level of measurement does the Final Exam Points variable represent: Is the data discrete or continuous? Is the data qualitative or quantitative? Is the data nominal, ordinal, ratio, or interval?

7. Use SPSS to output the mean, median, and mode for the Final Exam Points. Include the SPSS here. Which of the three descriptive numerical measures of central tendency (mean, median, or mode) BEST describes the variable Final Exam Points? What information does the measure tell you about the students in the dataset (Stat_Grades.sav)?

8. Which descriptive numerical measure of central tendency is LEAST appropriate to describe the variable Final Exam Points? Use SPSS to output ONLY that one numerical measure. Include it here. Why is that numerical measure the least appropriate? What information does that measure tell you about the students in the dataset (Stat_Grades.sav)?

9. Choose the most appropriate graph to represent the variable Final Exam Points. Create the graph in SPSS and include it here. Be sure the graph is fully labeled. Discuss why you chose this graph type and what it tells you about the students in the class.

(For questions 10-13): Relationships (correlation) between variables.

10. List all five quizzes, and include for each quiz, the numerical measures of mean, range, and variance. Explain what these measures tell you about the quizzes as compared to each other. On which quiz did students appear to perform the best? Which quiz had the lowest performance? Which quiz had the highest variance (variation in scores) and what does that tell you about that quiz? (100 word minimum, fully explain, include SPSS).

Fill in this table, include the SPSS, and then explain and answer the other questions.

11. Looking at the relationship between each of the Five Quizzes and the Total Points: First, use SPSS to measure the relationship (correlation) between each Quiz and the Total Points. Include all five r –values here. Which of the five Quizzes has the strongest relationship (correlation) with the Total Points, and how do you know? Which of the five Quizzes has the weakest relationship with the Total Points, and how do you know?

Quiz 3 has the strongest relationship with the Total Points variable, since the correlation value of 0.83 is the closest to 1 or -1. Quiz 5 has the weakest relationship with the Total Points variable, since the correlation value for Quiz 5 is 0.65, which is the closest to 0 of the five correlation coefficients.

12. Use SPSS to create the scatterplot for the Quiz and Total Points that had the strongest relationship. Paste the graph here. What does this graph show or tell you? Is it linear? Is the slope positive (going upwards) or negative (going downwards)? Does it seem like doing well on the Quiz relates (or correlates) to doing well on the Total Points?

13. Will a low score on the Quiz cause a student to get a low value on the Total Points? Explain. (50 word minimum)

14. Which two variables are being investigated and label each variable as either dependent or independent.

15. The Correlation Coefficient (or r-value) is used to measure the relationship between any two variables. In this case, what is the r-value?

16. What does the r-value and the scatterplot tell you about the relationship between these two variables? Is the relationship positive or negative? Is it strong, medium, or weak?

17. Suppose a student has a previous GPA of 3.20. Using the scatterplot, what is a good estimate of what their Final Exam Points?

1. Using the Variable View in SPSS (lower left), write out how Ethnicity is labeled, and note how many Ethnicity categories are included.

2. What type of data and level of measurement does the Ethnicity variable represent: Is the data discrete or continuous? Is the data qualitative or quantitative? Is the data nominal, ordinal, ratio, or interval?

3. Use SPSS to output the mean, median, and mode for the Ethnicity. Include the SPSS here. Which of the three descriptive numerical measures of central tendency (mean, median, or mode) BEST describes the variable Ethnicity? What information does the measure tell you about the students in the dataset (Stat_Grades.sav) – be specific?

4. Which of the three descriptive numerical measures of central tendency (mean, median, or mode) LEAST (or most poorly) describes the variable Ethnicity? Explain.

5. Choose the most appropriate graph to represent the variable Ethnicity. (There is more than one possible answer). Create the graph in SPSS and include it here. Be sure the graph is fully labeled. Does this graph confirm what the mode tells you about this dataset? Explain.

6. What type of data and level of measurement does the Final Exam Points variable represent: Is the data discrete or continuous? Is the data qualitative or quantitative? Is the data nominal, ordinal, ratio, or interval?

7. Use SPSS to output the mean, median, and mode for the Final Exam Points. Include the SPSS here. Which of the three descriptive numerical measures of central tendency (mean, median, or mode) BEST describes the variable Final Exam Points? What information does the measure tell you about the students in the dataset (Stat_Grades.sav)?

8. Which descriptive numerical measure of central tendency is LEAST appropriate to describe the variable Final Exam Points? Use SPSS to output ONLY that one numerical measure. Include it here. Why is that numerical measure the least appropriate? What information does that measure tell you about the students in the dataset (Stat_Grades.sav)?

9. Choose the most appropriate graph to represent the variable Final Exam Points. Create the graph in SPSS and include it here. Be sure the graph is fully labeled. Discuss why you chose this graph type and what it tells you about the students in the class.

(For questions 10-13): Relationships (correlation) between variables.

10. List all five quizzes, and include for each quiz, the numerical measures of mean, range, and variance. Explain what these measures tell you about the quizzes as compared to each other. On which quiz did students appear to perform the best? Which quiz had the lowest performance? Which quiz had the highest variance (variation in scores) and what does that tell you about that quiz? (100 word minimum, fully explain, include SPSS).

Fill in this table, include the SPSS, and then explain and answer the other questions.

11. Looking at the relationship between each of the Five Quizzes and the Total Points: First, use SPSS to measure the relationship (correlation) between each Quiz and the Total Points. Include all five r –values here. Which of the five Quizzes has the strongest relationship (correlation) with the Total Points, and how do you know? Which of the five Quizzes has the weakest relationship with the Total Points, and how do you know?

Quiz 3 has the strongest relationship with the Total Points variable, since the correlation value of 0.83 is the closest to 1 or -1. Quiz 5 has the weakest relationship with the Total Points variable, since the correlation value for Quiz 5 is 0.65, which is the closest to 0 of the five correlation coefficients.

12. Use SPSS to create the scatterplot for the Quiz and Total Points that had the strongest relationship. Paste the graph here. What does this graph show or tell you? Is it linear? Is the slope positive (going upwards) or negative (going downwards)? Does it seem like doing well on the Quiz relates (or correlates) to doing well on the Total Points?

13. Will a low score on the Quiz cause a student to get a low value on the Total Points? Explain. (50 word minimum)

14. Which two variables are being investigated and label each variable as either dependent or independent.

15. The Correlation Coefficient (or r-value) is used to measure the relationship between any two variables. In this case, what is the r-value?

16. What does the r-value and the scatterplot tell you about the relationship between these two variables? Is the relationship positive or negative? Is it strong, medium, or weak?

17. Suppose a student has a previous GPA of 3.20. Using the scatterplot, what is a good estimate of what their Final Exam Points?

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