Compute S X, S X2, S Y, S Y2 and S XY. Using these values find the regression coefficients a and b of the straight line:
= a + bX
provide verbal interpretation of the coefficient b
QSCI381: Introduction to Probability & Statistics
Problem set #9
Regression & Correlation
#1. The following data is from a random sample of baby sparrows:
|
Age (days) X |
Wing length (cm) Y |
|
3 |
1.4 |
|
4 |
1.5 |
|
5 |
2.2 |
|
6 |
2.4 |
|
8 |
3.1 |
|
9 |
3.2 |
|
10 |
3.2 |
|
11 |
3.9 |
|
12 |
4.1 |
|
14 |
4.7 |
|
15 |
4.5 |
|
16 |
5.2 |
|
17 |
5.0 |
Compute S X, S X2, S Y, S Y2 and S XY. Using these values find the regression coefficients a and b of the straight line:
= a + bX
provide verbal interpretation of the coefficient b
2. What is the standard deviation of regression (Se)? Explain why it differs from SY.
3. What is the estimated mean wing length of a 13 days old sparrow?
4. Compute the coefficient of correlation r.
5. Run the regression on MINITAB or Excel and verify the values of a, b, Se, r obtained in 1-4 above.