1. In the text, a correlation matrix was described. Using your own words, ex- plain what is meant by a correlation matrix. What values appear along the diagonal of a correlation? How do we account for these values?
2. An investigator studying the effects of stress on blood pressure subjected mine monkeys to increasing levels of electric shock as they attempted to ob- tain food from a feeder. At the end of a 2-minute stress period, blood pres- sure was measured. (Initially, the blood pressure readings of the nine mon- keys were essentially the same).
|
Blood Pressure
Y
|
Shock Intensity
X
|
|
125
|
30
|
|
130
|
30
|
|
120
|
30
|
|
150
|
50
|
|
145
|
50
|
|
160
|
50
|
|
175
|
70
|
|
180
|
70
|
|
180
|
70
|
Some helpful intermediate calculations: X = 450, Y = 1365, X 2 = 24900, Y 2 = 211475, ( X)2 = 202500, ( Y)2 = 1863225, X Y = 71450,
and ( X)( Y) = 614250. Using this information,
a. Plot the scatter diagram.
b. Determine the regression line relating blood pressure to intensity of shock.
c. Place a 95% confidence interval on the slope parameter 13.
d. Test the null hypothesis of no linear relationship between blood pressure and shock intensity (stress level). (Use a = 0.01.)
e. For a shock intensity level of 60, what is the predicted blood pressure?