Statistics Correlations for Absences and Final Grades

1. You are given the following data.
Number of
Absences Final grades

0 96
1 91
2 78
2 83
3 75
3 62
4 70
5 68
6 56

a. Make a scatter plot for the data. You do not need to turn this in, but based on your scatterplot, does it look like the correlation is significant?

B. Does it look like the correlation is positive or negative?

Answer: Negative (inverse) is this correct?

c. Find the correlation coefficient for the data.

Answer: Correlation Coefficient = -0.912 (Estimated using CORREL function in Excel) is this correct?

d. Find the equation for the regression line for the data.

2. "Name" two variables that have a positive relationship, two that have a negative relationship and two that do not have a relationship.

3. A psychologist looks at the relationship between emotional sensitivity in men and their physical health. He proposes that men who are in touch with their emotions are more healthy. He obtains r = .08.

- What is his null hypothesis?
- What would be the value of r for the null hypothesis?
- What is his alternate hypothesis?
- What did his data find?

4. Suppose r = 0. What is the slope (provide your answer both as a calculation and a description of what the slope of the regression line would look like)?

- What is the y-intercept (provide your answer as a calculation)?
- Why does your answer for the y-intercept make sense?

5. Suppose we wanted to look at the frequencies at which children present with certain psychopathologies. We obtain the following data on 50 children at a treatment facility:

Depressive Disorders 14, ADHD 8, Anxiety Disorders 15, Psychotic Disorders 5, Eating Disorders 8.

a. What is the null hypothesis?
b. What are the expected frequencies?
c. What is the df?
d. Calculate x2
e. Discuss your findings