Calculate the correlation between the variables.
Discuss perfect correlation and negative correlation.
Use the following data to answer these questions regarding correlation:
The state of Vermont is divided into ten health planning districts, corresponding roughly to counties. The data for 2002 represent the percentage of newborns under 2500 grams (Y), the fertility rate for females ≤17 or ≥35 years of age (X1), and the percentage of births to unmarried mothers (X2) for each district:
|
District
|
Y
|
X1
|
X2
|
|
1
|
6.1
|
43.0
|
9.2
|
|
2
|
7.1
|
55.3
|
12.0
|
|
3
|
7.4
|
48.5
|
10.4
|
|
4
|
6.3
|
38.8
|
9.8
|
|
5
|
6.5
|
46.2
|
9.8
|
|
6
|
5.7
|
39.9
|
7.7
|
|
7
|
6.6
|
43.1
|
10.9
|
|
8
|
8.1
|
48.5
|
9.5
|
|
9
|
6.3
|
40.0
|
11.6
|
|
10
|
6.9
|
56.7
|
11.6
|
a. Calculate the correlation between Y and X1. Discuss your results in terms of what the correlation coefficient means with respect to the relationship between Y and X1.
b. Calculate the correlation between Y and X2. Discuss your results in terms of what the correlation coefficient means with respect to the relationship between Y and X2.